What's the Mathematical Difference Between Andy Dalton and AJ McCarron?

Andy Dalton's thumb may not be healed for the Bengals' game against the Steelers on Saturday. And that's a big deal.

One of the bigger storylines entering this weekend's NFL wild card games surrounds the quarterback situation in Cincinnati. 

Will Andy Dalton's thumb be good to go, or will AJ McCarron get the nod once again?

It's a big deal -- the quarterback position is the most important in football, and one option is a clear upgrade over the other.

But, mathematically, how much does this all matter?

Fortunately, we have metrics to help show the difference between Dalton and McCarron. 

If you're newer to numberFire, you may not be aware of our Net Expected Points (NEP) metric -- it's our way of showing the true contribution a player makes on the field. You see, yards, touchdowns and interceptions don't tell the entire story about a player. Why should a 15-yard gain on 3rd-and-20 be considered just as impactful as a 15-yard gain on 3rd-and-14? 

It shouldn't. One results in a first down, while the other sees the team lining up to punt or kick a field goal.

NEP takes down-and-distance scenarios, sees how a player changes that scenario from one play to the next, and credits -- or discredits -- the player accordingly. To get more info on it, check out our glossary.

In 2015, Andy Dalton didn't finish with the highest Passing Net Expected Points total (points added through the air) in the league, but that was only because he was injured. The fact is, among relevant quarterbacks this season, Dalton had the highest per drop back efficiency in the league.

Andy Dalton. King of efficiency. Real life.

His 0.35 Passing NEP per drop back mark was just a smidgen better than Carson Palmer's average, and it was actually a top-10 average since the turn of the century. Pretty crazy considering Dalton's previous four seasons ended with 0.02, 0.02, 0.09 and 0.05 Passing NEP per drop back rates.

The thing is, McCarron hasn't been so bad himself. In limited time -- 131 drop backs -- McCarron has a 0.18 Passing NEP per pass average. Now is probably a good time to mention that this doesn't mean he was 0.18 points per drop back better than an average quarterback. Since NEP analyzes each play, runs and passes are compared to one another. And passing is far more efficient than rushing, so numbers tend to skew above zero.

The truth is, the average quarterback drop back in 2015 yielded 0.15 Net Expected Points. So McCarron has performed just a tad above average.

But the difference between Dalton and McCarron on each drop back is roughly 0.17 expected points, which is a pretty significant gap when you figure the Bengals' quarterback is going to drop back around 40 times -- at least -- in Sunday's matchup. 

This isn't to say we should expect more than a touchdown swing in points, especially when taking a look at Andy Dalton's historical play against common opponents, as well as his performances in the playoffs. But there's no doubt that the Bengals would be favorites if he was healthy. Now, the game is completely up in the air.