We spent a fair amount of time talking about this match on Thursday night's podcast if you are interested in that sort of thing. Coming into this match, form might be one of the most discussed topics. Seattle has earned just two points in its last four games, while Portland has earned eight points over that same span. In my opinion, form only means something if there's an obvious reason as to its recent fluctuation. For Seattle, there is no obvious reason for its poor play. Seattle has been bad the last four matches in terms of results, but they have actually outshot those opponents 56-to-41.
The real effect on form this game will likely be the fact that Brad Evans and Eddie Johnson are out due to international duty---technically, though in Johnson's case it's more his injury that's going to keep him out. The Timbers will be without Rodney Wallace, Ryan Johnson and Alvas Powell. However, the Timbers' Johnson is not nearly the potential threat as that of the Sounders, and Powell has been in a reserve role since the return of Jack Jewsbury and Futty Danso. The absences seem to favor the Timbers.
The stats suggest that Portland is a somewhat heavy favorite this match. Playing in front of Jeldwen's home fans, with better shot rates and finishing rates on the season, our model suggests the Timbers have a 52-percent probability of winning against the Sounders' 19 percent. This really shouldn't be surprising, as we've seen the strong predictive ability of both home-field advantage and shots rates. What might be slightly more surprising is the effect of this match on the Supporters' Shield race.
In the event of a Portland win, our season simulation suggests Portland would catapult to nearly a 45-percent chance at (at least a share of) the Shield, and Seattle would fall to below five percent (2.3%). However, if Seattle pulls off the upset, it would improve its chances to 26 percent, while simultaneously dropping Portland to virtually zero percent. A tie would actually be the combined worst-case scenario for the two teams. They currently share 38-percent chances at the overall top seed, but a tie would leave the Sounders at 12.4 percent and the Timbers with 0.3 percent, allowing New York (45.3%) and Sporting Kansas City (42.8%) to fight over the Shield.
These two teams are almost sure to make the playoffs, regardless of tonight's outcome. But a top-seed and the prospect of home-field advantage in a potential MLS Cup Final no doubt elicits some drooling from both sets of supporters.