ASA Roundtable: The One About Home-Field Advantage
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Alex Bartiromo
With a break in the MLS Postseason schedule, we here at ASA figured we’d give you something just as good as a second leg (RIP), and a good deal more wholesome than another Toronto/Seattle MLS cup final: another roundtable! This week, our question comes from contributing writer, WOWY inventor, and tactician extraordinaire Cheuk Hei Ho.
Cheuk Hei Ho [Blogger at TacticsPlatform]
Should the away team press as aggressively as they do at home?
Alex Bartiromo
As always, if you have any questions you want asked, email us at ericansocceranalysis@gmail.com or hit us up on Twitter @AnalysisEvolved. Don’t forget to hit that like button, and subscribe to our Patreon if want to see more of this kind of analysis.)
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Ian L [Featured Writer, Co-host of American Soccer Analysis Podcast]
Why would they not? Sleepy? Cramped legs? Just watched “Must Love Dogs” on a commercial flight and are too emotionally fraught to press properly?
Matthias Kullowatz [Data Scientist, ASA database manager]
When I own a team, they’re only allowed to watch 300 on the flight.
Ian L
I wonder if sometimes this is what home field advantage is.
This idea that teams should only play for a draw or dial back their press or whatever.
Matthias Kullowatz
This is my theory. I found some data to support it back when I was a contributing member of this website.
Ryan Anderson [Contributing Writer, Founder of MLS Fantasy Stats, Certified USSF Referee]
Another way to look at this would be to investigate documented causes for home field advantage and determine whether or not pressing increases or decreases the likelihood of those events.
Ian L
What are some documented causes, for example?
Ryan Anderson
My thoughts go to refereeing. If you're sitting back and letting the home team have control, the home crowd is gonna be in the game more and may have more of an impact on the referee's unconscious bias (as documented by the book Scorecasting). Not only that, but you're offering a much greater chance of a penalty going against you due to the ball constantly being on your side of the field, in and around your penalty area.
Jamon Moore [Contributing Writer, blogger at Quakes Epicenter]
Having asked Matias Almeyda about this phenomenon, I can say that the aggressive pressing/man-marking style didn't change on the road, and it didn't produce the results he expected. He seems baffled by the home/away dynamic in MLS.
It's almost like it's in the subconsciousness of the players at this point that they are not likely to get a result, and changing that will take some time.
Ian L
Let’s just break this all down.
Reasons why I hear it’s hard to win on the road:
1. Travel is hard
2. The ref’s unconscious bias
3. Fans?
Jamon Moore
4. The players don't expect to win.
Ian
Yes, but I’m trying to find out why.
Why is there this built-in attitude that you can’t win on the road?
And this is the cycle, man.
This is what I’m saying.
Eliot McKinley [Contributing Writer]
Because teams don’t win on the road.
Ian L
Which came first, the poor away form or the egg?
If your away form falls in a forest and there’s nobody around to hear it can it explain these differences in PPDA?
Eliot McKinley
It has been getting worse.
Home field advantage has been falling across Europe for the last couple decades, with the possible exception of the Premier League. MLS continues to MLS by bucking that trend. pic.twitter.com/7KbM3ki5xU
— Eliot McKinley (@etmckinley) September 11, 2019
Ian L
That is what cyclical problems do!
They get worse!
Eliot McKinley
But only in MLS.
Ian L
So, the answer is… less travel?
Or just not having the idea built into your head that the travel has made it very difficult for you to win.
Jamon Moore
Charter flights in the CBA! Forget that pay raise, just fly in comfort.
If I had to fly every week, and my company said: we can give you a raise or we can give you first class on every flight with a special security clearance—I might take the first class.
Ryan Anderson
One reason travel may not show up in home field advantage studies as much is that those studies are done in nations the size of Wisconsin. In the US, with 1500-mile trips, travel may have a larger impact.
Though I personally don't see how much sleeping in one's own bed or not having to travel makes that much of a difference on someone's performance. Does a change in routine make that much difference?
Alex Bartiromo [Contributing Writer, Chat Collator]
I definitely see how it could. Cramped seats, a disturbed sleep schedule, having to be in airports constantly. Travel is exhausting.
Eliot McKinley
Tiotal Football looked into this travel issue a while back. If I remember it correctly, there wasn’t a lot there. At least on a miles traveled basis.
Ian L
I think we also need to look at something along the lines of say:
Does MLS have teams that are actually good enough that they can reasonably expect to win on the road consistently?
In the “euro” leagues you definitely have an upper tier of teams that are expected to win no matter where they travel.
I don’t think that exists here.
Cheuk Hei Ho
LAFC.
Ian L
Maybe we could look at LAFC this season and see how a team that’s obviously much better than the other teams fares on the road.
And maybe the answer is as simple as that MLS teams aren’t that much better than other MLS teams and so any small advantage a home team gets from whatever factors is enough.
Eliot McKinley
2 teams won more than lost away, NYCFC and LAFC.
Last year there were 4.
Alex Bartiromo
To reformulate the question a bit: do we think the bigger effect on away teams comes from the psychological aspects (of both the players and refs) or the physical aspects (for the players)? Do we see home field advantage changing in MLS in the next ten years?
Eliot McKinley
Is it worthwhile to just step through the possible reasons for home-field advantage one by one, comment, and then move on?
So first off, travel. Is it because teams are often flying thousands of miles in coach class seats to play away games?
We found no direct correlation between miles traveled and results a few years ago. https://www.americansocceranalysis.com/home/2015/5/20/zrq8500mrlga9pnts3basp37l2yi7r
Ian L
You’re talking about cramping on planes?
I’ve heard that before.
I’m not convinced.
Eliot McKinley
Jet lag, etc.
Ian L
Possibly?
idk
Not sleeping in your own bed?
Maybe?
These all seem like things that professional athletes would have to learn to deal with at some point.
Eliot McKinley
But the Australian A-League doesn’t have a huge home advantage. Neither do NWSL or USL Championship.
Jamon Moore
Here’s what Wondo thinks about the issue:
Joel: I mention charter flights because it’s been a topic of conversation all season long. Has there been an instance that you can think back to where you were like, ‘wow this was a logistical nightmare?’
Wondo: Oh, yeah. We have a few, especially when you’re on the road when we’re going from Salt Lake to New York City, and we’re flying back from the game and we’re in the airport. I remember two years ago we were going to DC, and I think we were at the airport for 8 hours. Flight got delayed and then the flight got cancelled. It was just an absolute logistical nightmare. We were pretty lucky this year with delays and things of that nature. But I know Montreal had a nightmare. I think New England as well, where they’re arriving to the game and it’s tough.
Ian L
So, the occasional airport nightmare, sure.
I can see that causing some issues.
Carlon Carpenter [Contributing Writer, UVA Performance Analyst]
It’s not solely an MLS issue, either. That ESPN article on sleep recently was super poignant.
Ian L
So we could get rid of home-field advantage with some Benadryl and an in-flight showing of Seven Years in Tibet
Everybody nice and rested.
Carlon Carpenter
Yes.
Next CBA.
I’m in charge of movies when we travel and I start the journey with something relaxing, and end it with a thriller.
Tactical Movie Periodization.
Jamon Moore
Start all MLS games at the same time across time zones so there is no jet lag. 8pm ET/7pm CT/5pm PT.
Everyone knows Mountain Time doesn't really exist.
Ian L
So just logistics really is the issue here.
Traveling is a hassle.
I get that.
Maybe after a day of flying you need more than a day to get into a highly competitive soccer mindset?
Carlon Carpenter
I know how MLS players feel regarding no chartered flights with tons of luggage, players who are dumbasses, etc.
But on the player side, with proper planning, etc. a lot of the effects it would have on performance can be negated.
Jamon Moore
Didn't Andrew Carleton just miss a game because he forgot his passport to Canada or something?
Ian L
Happens more than you’d think.
Teams are supposed to have somebody on staff whose job that is, too.
Carlon Carpenter
We had a player forget his boots and wallet. Last week.
Jamon Moore
Coaches really are just better-paid babysitters.
And some are not better paid.
Eliot McKinley
Ok. Travel is covered. What about increased referee bias in MLS?
Cheuk Hei Ho
The thing is that it’s difficult to show that.
Should we focus on foul/tackle?
Or fouls/opp. passes or touches?
Eliot McKinley
Are refs in MLS more afraid to make a call against a home team because of fan reaction compared to other leagues?
Cheuk Hei Ho
Wow, it’s even more difficult to compare ref bias between different leagues.
Eliot McKinley
I’d think refs feel less pressure overall in MLS than in many other leagues. But Atlanta’s penalty numbers may suggest they are biased towards them.
Ian L
Do home teams get more penalties?
I’m going to assume so but idk
How big of a bias swing are we talking here?
Eliot McKinley
Here’s penalties home/away over the last few years.
But this discrepancy could be because away teams don’t make it to the box as much.
Ian L
1.4 [ratio of home/away goals in 2019] doesn’t seem like a huge amount across the whole league?
But that’s a really interesting trend.
2016, wow.
That’s huge.
Eliot McKinley
I know, before soccer was invented in Atlanta.
Jamon Moore
Should we check successful passes and dribbles in the box as a proxy to penalty ratio?
Ian L
I swear somebody here looked at touches in area and compared them to penalties and there was no real correlation worth noting.
But I’d be happy to see it again.
Eliot McKinley
2019 final third touches.
PK ratio was 1.41.
Ian Lamberson
But shouldn’t we compare that to final third fouls and not penalties?
Lots of those close fouls end up getting spotted outside the box.
Eliot McKinley
Final third fouls suffered.
Other year’s touches.
Ian L
So that stays fairly consistent.
Tiotal Football [Contributing Writer, ASA/Dirty South Soccer]
If I'm following along, there’s generally a slightly higher ratio of fouls called to touches and a slightly higher ratio of PKs to fouls called and touches for home teams.
Eliot McKinley
EPL PKs.
EPL final third touches.
EPL final third fouls.
So, not that different from MLS except that 2016 PK ratio.
I’d sum it up as: refs are slightly biased to home teams, but probably not more than other leagues. So that probably doesn’t explain why MLS home advantage is bigger.
What about playoffs/no pro-rel?
Ian L
This makes sense to me and is the first step in my cyclical spiral of road game mediocrity.
Eliot McKinley
But A-League, Liga MX, NWSL, and USL have playoffs and not a huge home advantage.
Ian L
Hmm, is it possible that MLS teams just suck?
Eliot McKinley
I guess we can add parity in here too.
Ian L
Parity is a big thing, yeah.
Maybe MLS teams aren’t that much better than each other so any slight advantage is enough to tip the scales.
Eliot McKinley
MLS has higher parity than most Euro leagues by Gini.
Tiotal Football
It's the parity, lads.
Eliot McKinley
This past season:
Tiotal Football
Being really careful not to get the causation backwards, we could look at all teams’ even game state home/away xGDs bucketed by PPDA [Passes per Defensive Action] in even game states or something like that.
Or even just look to see if teams press more at home than away.
Ryan Anderson
Didn't someone have a team style difference metric they created?
Eliot McKinley
It was year to year by passing, but we could do it home and away as well.
Ryan Anderson
One of the main points for describing home-field advantage in the Scorecasting book was that a team's playstyle or ability really wasn't that much different home vs away, and so it didn't play into home-field advantage. If we can demonstrate a marked shift in strategy for each team playing home versus away, we can show MLS to be the exception to that generality.
The trick would be to separate that style difference from a simple response to the higher pressure of the home team.
I.e., do home teams press higher because away teams are sitting back or vice-versa? Another classic chicken-and-egg scenario.
Tiotal Football
Most everyone presses more at home in every score state.
Can someone dissuade me from saying that is definitive evidence that teams set up to play differently at home vs away (something we already knew)?
I think probably most persuasively, the lion's share of teams are pressing much less vigorously on the road when the scoreline is level.
Eliot McKinley
Portland crosses a lot at home.
If you are playing the same style home and away, they should have similar passes over/under-represented for both. That seems to be the case for some, but mostly not.
Tiotal Football
There is also player rotation.
(Can't remember if we did this.)
Ian L
What about support from the fans?
Portland's fans will them to new heights of crossing.
Through passion.
Ok back to the topic at hand.
There is a lot of player rotation in MLS, but I don’t think home/away is a big reason for it.
Tiotal Football
Yea i think we're at the point, though, where we can confidently say teams set up to play differently on the road - and maybe one of the last confounding factors to choke out would be player rotation.
Before you move onto "why do they do that?"
Ryan Anderson
There was that one time where Zlatan was limited medically and he didn't want to play on turf, but that's probably the exception rather than the rule.
Ian Lamberson
He and Drogba did do that, yeah.
I guess what I'm saying is that I don't think that there is a lot of player rotation that happens because you're away from home. I think most player rotation has to do with the regular injuries/suspensions/international duties etc. and they get rotated regardless of whether or not they are at home or on the road, and in order to try and pin this on player rotation I think we'd have to show this not to be true. And if I'm following our thread, we'd also have to show that they rotate on the road more than other leagues do.
I don't think we'll get there.
I'm not even sure how one would be able to quantify this.
Tiotal Football
I think we have the data to do an intra-MLShome/away rotation comparison.
Do we have the will? Almost certainly not.
Ryan Anderson
If they do rotate on the road, it's probably just for a couple games at most, especially during the international breaks or during double game weeks.
Eliot McKinley
But this all goes back to the circle of “we can’t win on the road so we won’t try”.
Ian L
Yes. Which I still like.
Tiotal Football
If there's parity, why would you think that?
We should ask Sean Davis.
Ian L
If you are playing not to lose aren't you more likely to draw at best?
Which brings down the points you get on the road.
Which in turn reinforces the belief that it's impossible to win on the road so you should just go for a draw.
Which in turn lowers points teams get on the road.
Which in turn
Etc.
Tiotal Football
Is the hypothesis you are teasing out that this is all placebo?
Feedback loop etc.
Ian L
Yes.
Not entirely, mind you.
I think parity probably has a lot to do with this as well.
So, we have parity which exacerbates whatever small advantages home teams have intrinsically. This lowers the team’s success rate on the road. This reinforces that teams are rarely successful on the road so getting away with a point is a very good result! This gets teams to play more conservatively which in turn lowers the rate of success on the road which reinforces the cycle.
Eliot McKinley
What about referee bias?
Would the refs have bigger bias in MLS than anywhere else?
If that is all there is to it.
Ryan Anderson
Good point. Especially in soccer, because of the inordinate effect penalties and red cards can have on game outcomes.
Eliot McKinley
PRO, QED, I guess.
Ian L
I'm not sure I buy the ref bias thing, honestly.
I'm sure it's there.
But I want to put it in that box with fan support.
Tiotal Football
If anything the EPL refs seemed hella persuaded by the home crowds there to give penalties.
Which... with the parity thing, you'd think there should actually be a difference in the other direction.
Ryan Anderson
I think we already showed that the refs are just as home-biased as the rest of the world.
The bias actually has to do with fan support.
The larger the crowd and the more skewed the audience is toward a team, the more bias there is. It's unconscious bias, though.
Ian L
Atlanta obviously wins because of its tremendous atmosphere and passion.
Tiotal Football
Hold on.. just thinking through something.
if refs give penalties out equally in EPL and MLS, but MLS teams have the bigger H/A [Home/Away] advantage and the lower gini...
Is it just the case that a penalty (decided by the ref due to the normal ref h/a bias) is less surmountable in MLS whereas it's not in leagues with no parity?
I think it's the case that the refs gives out a penalty to Watford sometimes when Man City is there, but Man City kills them anyways cuz less parity.
In MLS, the ref sometimes gives out the penalty to Chicago, but Philadelphia isn't able to overcome it because of parity.
Thus leading to higher H/A at the mean.
Ryan Anderson
Games played on neutral pitches and closed games have practically no referee bias.
Eliot McKinley
Has that been independently verified?
Ryan Anderson
Yeah, at least that's what Scorecasting said. And closed games, even if played on home turf, have practically no referee bias and no home-field advantage.
Eliot McKinley
I assume they mean not losing. MLS teams win ~50% of the time.
*MLS since 2002 (Scorecasting was written in 2011)
Tiotal Football
If I had access to data across the streams, I would look at the distribution of GD after teams concede penalties home and away in England and in MLS.
Are the top table teams doing disproportionately well after conceding penalties in England compared to MLS?
If so, you could end up with H/A splits that are lower in England compared to MLS and the ref bias plus parity arguments in the club house.
Alex Bartiromo
Here's what I'll say:
1) I think that interviewing more players about this would really help our understanding here. Understanding what they think causes this split could point us towards a good set of questions. We should reach out to Benny/Sal/Ike (idk) and ask anyone we interview in the future.
2) Conclude your thoughts. This is long and complex enough.
Dummy Run [Featured Writer]
In conclusion, home advantage is critically important in MLS because an American League team should never have to play in a National League ballpark.
Ian L
My conclusion hasn't changed. I think this is one part parity and two parts fairy dust. I will concede that some unconscious ref bias exists, fan support helps to some degree, and flying the day before isn't the ideal way to prepare your body for soccer, but none of these things on their own or even together is enough to make up for the vast difference we see in results. It is enough for a start, though, and that seed of doubt has weighed on the mind of countless managers who are hoping to get out with a draw. After that it's somewhat cyclical. I think teams should play more proactively on the road and a team that does commit to it will be surprised at how often they can find success. Maybe.
Cheuk Hei Ho
I thought your theory about MLS teams only needing to win at home to be in the playoff hence no motivation to fight on the road was great.
We should try to test that.
Ian L
But we didn't see that disparity when we looked at other leagues with similar systems.
Though I wouldn't be surprised if it factored in some.
Cheuk Hei Ho
Did we not? Very few leagues allow so many teams in the playoffs.
Ian L
Hmm. That could be a good point Cheuk.
I'm not sure we thought about that.
Cheuk Hei Ho
I really think that a lack of motivation to be really good is a big factor in home/away difference. Well, I hope it is just because it's a very cool hypothesis.
Eliot McKinley
6/11 teams make the playoffs in the A-league.
Ian L
Well, there you go.
6 of 11?
Geez.
Wild.
Eliot McKinley
Echoing Ian, aside from potentially a larger effect from travel, I don’t see any of the usual home field advantage explanations to be more applicable in MLS than other leagues. That leaves parity and a belief in the anti-prosperity gospel among MLS teams when playing on the road as the drivers of the huge home advantage.
Matthias Kullowatz
What about this: look within each game for periods in the first half where the score is tied, and periods in the second half where the score is tied. You could even break it into 1-2-minute intervals. Then calculate (from home perspective) xGD per X minutes of tied game state in first half and xGD per X minutes of tied game state in second half, aggregate across all games, compare.
I think what you'll see is that the away teams xGD gets even worse in the second half in these even game state situations. Either they suddenly got worse, or they start employing bad tactics.
bad = overly conservative
You could pick other differential statistics, too.
Alex Bartiromo
That’s it for our roundtable, ~~playoff edition~~. We hope you enjoyed the conversation. If you have any thoughts on this topic, or if you have any questions you want asked, email us at olsendre@gmail.com or hit us up on Twitter @AnalysisEvolved. Don’t forget to hit that like button, and subscribe to our Patreon if you like the work we do.