The regular season has ended. Here are the final power ratings from an… unconventional… 2020 Major League Soccer campaign:
The teams’ playoff seeds are on the right (pale yellow is second-round home seeds, pale orange is second-round away seeds, pale red is first-round participants). As you can see, there are three outliers in terms of finish compared to team quality: Houston and Chicago, who missed out on the playoffs despite solid seasons, and Montreal, which qualified despite being one of the four-worst teams in MLS.
The Dynamo and Fire were marginally unlucky over the course of the year, but particularly for Houston, there’s a gulf between “marginally unlucky” and “finishing at the bottom of the Western Conference table by a pretty wide margin.” Some of that is the nature of averages and outliers: the Dynamo were often slightly below-average, and occasionally waaaaay above it. That can combine to look solid, but when each game (no matter how good) is worth a maximum of three points, the above-average performances can only be so meaningful. For Chicago, it was a similar story, but even more inconveniently placed: create a ton but don’t finish in the wrong games – such as a home loss to New England – and the cost on the table is worse than the cost in aggregate.
Montreal was just very lucky (with the typical caveats about what “luck” means in this situation) overall, and on a goals basis – rather than expected goals – the Impact was pretty close to average, which is… about where the finish in the table ultimately fell.
Coincidentally, the third seed in each conference was an OK team in xG terms that got incredible luck over the course of the year. I think in both cases, there’s an argument to be made for “get a lead, then bunker” strategies plus above-average finishing (Ebobisse/Valeri for Portland, Zelarayan/Santos/Zardes for Columbus) allowing the teams to play a type of game that isn’t going to impress in xG terms but is going to lead to results in the table.
Your Mileage May Vary as to whether pure creation is the be-all and end-all when it comes to looking forward and predicting the playoffs, or whether “finishing skill” is a true property of players/teams or a myth. There are arguments for either (and given the consistency of, say, Philadelphia to outperform its xG on such a regular basis, the truth is somewhere between).