Pro Football Focus has been one of Mitchell Trubisky’s biggest critics over the past couple of years, but on Thursday the site’s Twitter team reached a new low. On Trubisky’s birthday of all days, PFF decided to tweet a disparaging stat using their own proprietary “rating” stat. Worst of all, they didn’t even employ a sound statistical analysis when criticising him.
So how did PFF get it wrong? To start, the site unfairly uses the total number of games under a certain rating, since Trubisky has started more games since 2018 than any other QB listed in PFF’s tweet. Obviously this gives Trubisky more opportunities to have a bad game. A better way to judge these quarterbacks would be to look at the percentage of below average performances.
Since we don’t have access to the data that goes into PFF’s super secret formula of grading players, let’s just use the NFL’s standard passer rating. The average passer rating in 2018 was 94.1, and in 2019 it was 96.1, so let’s add up all the games each QB earned a passer rating below that mark, while also being mindful of the total amount of games each QB played. I’ve also removed all games with five or fewer attempts to eliminate outliers. In addition, I’ve added one quarterback that lots of Bears fans wanted the team acquire, instead of Nick Foles: Andy Dalton.
2018: Trubisky: 8/14, Allen: 10/12, Keenum: 12/16, Rosen: 14/14, Darnold: 8/13, Winston: 5/11, Dalton: 7/11
2019: Trubisky 10/14, Allen: 8/15, Keenum: 4/9, Rosen: 4/4, Darnold: 9/13, Winston: 8/16, Dalton: 10/13
Total games below average passer rating: Trubisky: 18, Allen: 18, Rosen: 18, Darnold: 17, Dalton: 17, Keenum: 16, Winston: 13
If you just look at total games under the average passer rating, it’s not good for Trubisky as he’s still on top. This time however, he’s joined by Allen and Rosen. But again, it’s not an equitable assessment, since Trubisky played more games than any other QB. So let’s calculate the percentage of below average games, and reprint that list.
Percentage of below average games: Rosen: 100, Dalton: 70.8, Allen: 66.7, Trubisky: 64.2, Darnold: 65.4 Keenum: 64.0, Winston: 48.1
Here we get a much clearer picture of all the quarterbacks’ performances. Should anyone be impressed with Trubisky, as 64% of his games fall below league average? Of course not. But it’s not fair to say he’s performed worse than Josh Rosen who has **never** finished a game above the league average passer rating.
As it is Trubisky’s birthday, let’s flip the script and cherry pick a nice stat of his, just like PFF cherry picked that bad one. How about this: In 2018, Trubisky set the Bears’ single-season record for completion percentage, at 66.6%.
Happy birthday, Trubisky. Don’t let the haters bring you down.