Fade Josh Allen’s Lofty Prop Bets in 2020

Expectations for Buffalo Bills quarterback Josh Allen have risen quite a bit ahead of the 2020 NFL season.

FanDuel Sportsbook has set Allen's props at 3,249.5 for passing yardage and 20.5 for passing scores. Reaching the over would result in Allen setting new career-highs in each category.

Trading for a receiver of Stefon Diggs' caliber is bound to improve a quarterback's prospects and based on the betting markets, that certainly seems to be the case with Allen.

Are Allen's props for the upcoming season too high? Are they not high enough? Is there any value to be had here?

Let's take a look.

2019 Production

Allen sat for much of Buffalo's Week 17 matchup with the New York Jets, but his full 16-game pace was to throw for 3,291 yards and 21 touchdowns. Both totals would eke out the 2020 overs by a smidge.

Allen started the 2019 season with three consecutive performances of 240-plus passing yards and subsequently reached that total just twice in the remaining 13 games. Given that he only topped 240 once as a rookie, it would seem that those first three games were an anomaly.

The 24-year-old averaged fewer than 7.0 yards per attempt in more than half of his contests and attempted 30 passes or less in more than half of them as well.

Among quarterbacks with at least 250 drop backs in 2019, Allen ranked 24th in Passing Net Expected Points (NEP) per drop back and 29th in Passing Success Rate (i.e., the percentage of drop backs that lead to positive NEP for a team’s offense).

2020 Outlook

Assuming a player will be on the field for a full 16 games is always a dangerous proposition, and that's especially the case with Allen. Going back to high school, Allen has suffered four different injuries to his throwing shoulder and elbow -- that includes a UCL sprain that forced him to miss four games as a rookie.

That said, is the addition of Diggs enough of a boost to make the overs worthwhile bets?

To better answer that question, I looked at three instances in the last two years where a team traded for an upper-echelon wideout to see how it affected the quarterback. The three signal-callers in question are: Baker Mayfield after the Cleveland Browns added Odell Beckham Jr. prior to the 2019 season, Jared Goff after the Los Angeles Rams traded for Brandin Cooks prior to the 2018 campaign, and Dak Prescott after the Dallas Cowboys' mid-season trade for Amari Cooper in 2018.

In the case of Baker and Goff, we're comparing the volume and efficiency from the season after the trade to the season immediately proceeding it. For Dak, we're looking at the nine games post-trade and comparing them to the seven pre-trade contests.

Mayfield After
Adding OBJ
Goff After
Adding Cooks
Prescott After
Adding Cooper
Passing Yards
Per Game
Passing Attempts
Per Game
Yards Per
Passing NEP
per drop back
Success Rate

There seem to be three distinct outcomes here.

Mayfield's production and efficiency decreased across the board. In fact, the 0.10 difference between his Passing Net Expected Points (NEP) per drop back from 2018 to 2019 was the same as the league average among quarterbacks last year. In other words, that's a rather sizable drop. It's worth mentioning that the addition of OBJ wasn't the only change Cleveland's offense experienced in 2019. Nevertheless, it's still noteworthy.

Goff saw his yardage per outing increase by nearly 40 yards, though much of that can be attributed to a rise of 5.3 pass attempts per contest. Aside from his Passing Success Rate (i.e., the percentage of drop backs that lead to positive NEP for a team’s offense), his efficiency metrics experienced only minute bumps.

As for Prescott, he was an entirely different quarterback. He averaged 71.8 more yards per game in the nine outings with Cooper than he did in the seven games without him. He also posted nearly an entire additional yard per attempt. His Passing NEP per drop back jumped from -0.02 (well below-average) to 0.16 (well above-average).

To which quarterback does Allen compare most? I'd argue that he's closer to Mayfield than he is to the other two.

Among the quarterbacks who are all but certain to start in 2020, only Mayfield, Sam Darnold, Daniel Jones, and Dwayne Haskins had a worse Passing NEP per drop back than Allen in 2019. Two of those were rookies. And only Darnold, Gardner Minshew, and Haskins had a lower Passing Success Rate.

According to NFL's Next Gen Stats, the only two passers with a worse completion percentage above expectation than Allen last year were Minshew and Haskins. In other words, those were the only two completing a lower percentage of passes that they should have been hitting.

Among next year's assured starters, only Goff and Darnold hit on a lower percentage of the deep throws they should have connected on.

Diggs is an excellent wideout, but unless Allen finds a way to actually improve his accuracy, there won't be much he can do.

If you're relying on volume to carry Allen to the over, you could end up sorely disappointed. The Bills had the seventh-lowest pass-to-run ratio in 2019 after having the fifth-lowest in 2018. The team drafting a running back in the third round for the second consecutive year is not exactly an indication that they're about to go pass-heavy with an inaccurate quarterback.

The Pick

In case it wasn't already clear, I prefer the under on 3,249.5 yards (-112).

Passing for 3,250 yards seems high for a guy with accuracy issues who might not even reach 475 attempts. numberFire projects Allen to throw for 3,476.6 yards, but that's based on a 518.4-attempt forecast. Even with the addition of Diggs, I don't see it.

As for touchdowns, 20.5 isn't a high number by any stretch. It's not a prop I'll be going out of my way to bet, but I will definitely be all over the under on yardage.