Blaine Gabbert Has Been Better Than Colin Kaepernick

Blaine Gabbert's reputation preceded him. Upon taking the 49ers' starting quarterback gig from Colin Kaepernick, San Francisco was 2-6 and struggling to score -- the 49ers had a combined nine points in the two games previous to Gabbert taking over, and they had failed to score more than seven points in four of their games with Kaepernick at quarterback. 

That's not to say Gabbert was a welcome relief, though. The former top-10 pick failed to really produce in Jacksonville -- he was unceremoniously traded prior to the 2014 season for a sixth-round pick after starting three games in 2013 where he threw one touchdown and seven interceptions. Needless to say, Gabbert's stock was not exceedingly high when he was named the starter prior to Week 9.

But since Gabbert has taken over, things haven't been so bad. The 49ers are 2-2, and while quarterbacks wins shouldn't be the end-all to a discussion, Gabbert has been far from the disaster many predicted. 

But just how good has Gabbert been, and is it sustainable for the rest of the season?

Gabbert vs. Kaepernick

Last week, we did a quick bit on how Gabbert compared to Kaepernick against common opponents. Combined against Arizona and Seattle, Kaepernick had 1 touchdown and 4 interceptions for a combined 191 yards. Gabbert, meanwhile, had 2 touchdowns and 1 pick with 582 yards. 

With four games under his belt this year, the Gabbert-Kaepernick comparisons begin to look to favor Gabbert even more.

These are pretty rudimentary stats, but the difference is pretty stark. Gabbert's current pace for the back-half games would put him pretty easily ahead of Kaepernick in each of these counting stats. From a raw numbers perspective, Gabbert is on pace for more yards and nearly twice as many touchdowns as Kaepernick was to start the year.

Luckily, we don't have to just rely on raw numbers. At numberFire, our signature metric is Net Expected Points (NEP). Details can be found in our  glossary, but NEP essentially measures how much a player is adding to or detracting from his team versus expectation.

There are 40 players with at least 100 drop backs this season. And looking at how Gabbert and Kaepernick rank within that group in Passing (points added on passes only) NEP per drop back among the group is actually pretty staggering:

The ranking pretty much tells the story, but there's even more here. Gabbert represents about a 0.14 increase in NEP on every single drop back over Kaepernick. What that means is  the 49ers can expect to score 0.14 more points per drop back with Gabbert under center versus having Kaepernick under center. 

That may seem like small potatoes, but it adds up -- on 33 drop backs (Gabbert is currently averaging 33.75 per game), the 49ers can expect to be over 4.5 points better with Gabbert over Kaepernick, without adjusting for strength of opponent. San Francisco is 1-1 in games decided by fewer than four points this year, winning the game with Gabbert under center, and losing the game with Kaepernick under center. That's potentially a two-win swing over the first 12 games, assuming Gabbert keeps that efficiency over the entire season.

That's strictly with their arms, of course. On 41 rushes this year, Kap actually added over 11 points with his legs, which is more than Gabbert's 10.88. And Gabbert's number is skewed dramatically by a touchdown run against Chicago that netted 5.10 expected points. The difference in rushing, though, doesn't come close to matching the difference in passing.

Despite his reputation, Gabbert has actually been okay this year. He's certainly better both by traditional and more advanced metrics than Kaepernick, at least. It'll be interesting to see how he's handled over the offseason.