The Washington Huskies entered Saturday’s game at Stanford as 13-point favorites (having been favored by as many as 17 on some online sports books last week) and left it with a second conference loss in three tries.

In the wake of the frustrating performance, some Husky fans called the upset the worst loss of Chris Petersen’s six-year tenure on Montlake, an argument Matt Calkins of the Seattle Times made in his postgame column. While Calkins offered a compelling case, I think the recency effect might overstate the pain of a fresh loss as compared to one in the distant past. So it’s worth considering this question from an unemotional statistical perspective.

Part of the challenge is defining the worst loss. As a result, let’s look at a variety of different methods of analysis before coming to a conclusion. First, what are the easiest games the Huskies have lost under Petersen? I’m basing this on Jeff Sagarin’s predictor ratings with an adjustment for home-field advantage. That yields the following top five (of 23 total losses in that span).

Year  Opponent          Loc  Rating
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2014  Oklahoma State     N     71.0
2018  California         A     73.0
2017  Arizona State      A     74.3
2019  California         H     75.6
2019  Stanford           A     76.3

This list features most of the usual suspects in the “worst loss” competition, including both of the Huskies’ 2019 defeats, last year’s loss at Cal and a 2017 loss at Arizona State. Yet the leader in this group, surprisingly, is the 2014 Oklahoma State team that defeated Petersen’s first UW squad in the TicketCity Cactus Bowl on Jan. 2 — quarterbacked by future Pittsburgh Steelers starter Mason Rudolph, then a 19-year-old true freshman.

That game topping the list shows the problem with considering the question simply in terms of opponent quality. While the Huskies were favored by about a touchdown, the outcome wasn’t a huge upset. Washington, which finished the season 8-6, was still a work in progress during Petersen’s first year at the helm. So let’s instead pose the question of which games the Huskies should have been favored by the most points in based on their own Sagarin rating, their opponent and the location. Here’s how that list looks.

Year  Opponent          Loc   xDiff
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2017  Arizona State      A     14.9
2019  California         H     11.6
2018  California         A     11.5
2016  USC                H      8.7
2015  Oregon             H      6.7

In part because we’re factoring the outcome of the game into this analysis, Saturday’s loss doesn’t crack the top five here. Based on current Sagarin ratings, we’d only have expected the Huskies to beat Stanford by about six points. If we go instead by pregame point spreads, Saturday’s -13 line ranks third-largest among losses in the Coach Pete era according to the Oddsshark.com database behind the top two games on this list. Washington was a 17.5-point favorite at Arizona State in 2017 and a 13.5-point favorite against Cal in week two. The next two games in terms of pregame line mirror the list above: last year at Cal (12-point favorite) and 2016 vs. USC (9.5-point favorite).

A final way to consider the question is how much the Huskies underperformed in a given game compared to what we’d expect the final margin to be based on their rating, the opponent and the location. That produces this top five.

Year  Opponent          Loc   xDiff   Score    Game
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2016  USC                H      8.7    -13    -21.7
2017  Arizona State      A     14.9     -6    -20.9
2015  (13) Utah          H      4.9    -11    -15.9
2019  Stanford           A      5.8    -10    -15.8
2015  Arizona State      A      5.2    -10    -15.2

Because of the 10-point margin, Saturday’s game pops back on the list, albeit still only in fourth. Surprisingly, the 2016 loss to the Trojans that ended Washington’s unbeaten season comes out number one. While that result forced the Huskies to play Alabama in the opening round of the College Football Playoff, it’s hard to say that even a double-digit loss at home was the worst of the Coach Pete era when it came against a stacked team with future No. 3 pick Sam Darnold at quarterback.

A case can certainly be made that given the way Washington was outplayed on both sides of the ball, the Stanford loss was even worse than the final 10-point margin — aided by a pair of goal-line stands — looks. But ultimately, I’m going with the 2017 loss at Arizona State as the Huskies’ worst under Petersen. That game, the biggest upset in terms of point spread, knocked Washington out of the Pac-12 Championship and contention for the playoff.

By contrast, it’s possible this year’s Huskies just aren’t as good as their New Year’s Six predecessors. It was easy to explain one big upset at home to Cal as a fluke product of an extended lightning delay. Two such disappointments in a four-game span are much harder to rationalize.

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