Let's be honest: Tim Tebow didn't lead the Broncos to their comeback victory on Sunday. He wasn't even on the field for the two biggest plays of the game: D.J. Williams' sack-strip-and-recovery at the Miami 36-yard line with 9:53 left in overtime (win probability added: plus-52 percentage points, according to ESPN Stats & Information) and Matt Prater's 52-yard FG four plays later (WPA: plus-44 percentage points). But it still makes as little sense to trash Tebow as it does to worship him: we just have to keep watching him play, until we see which triumphs, his alleged knack for winning or his supposedly objectively subpar quarterbacking skills.
Here's what we do know, however: After flailing against extra pressure just about all day, Tebow started blowing away Miami's blitz late in the fourth quarter and the Dolphins failed to adjust, which is what allowed the Broncos to pull into a last-gasp tie. Through the first 57 minutes, when Miami sent five or more pass-rushers, Tebow didn't complete a pass, scrambled just once for 5 yards and took four sacks. Against extra pressure in the final 10:31, however, he was 3-of-5 for two touchdowns, a first down and just one sack. Yet the Fins kept coming; they blitzed almost as often during that stretch as they had the entire rest of the game.
The Dolphins, you see, were blitzing the way most teams blitz: by feel. Defenses tend to add pressure when the situation seems to call for turning their intensity up a notch, and the more desperate the scenario, the more aggressive coaches get. But Total Quarterback Rating reveals that teams aren't blitzing anywhere near as effectively as they could be. In particular, it shows that defenses aren't paying enough attention to whom they're blitzing, as opposed to when.
This season, NFL starters have an average QBR of 60.2 when facing four or fewer rushers, and just 48.4 when facing five or more. But there's a lot of variation in how individual quarterbacks respond to blitzes. And check this out: the correlation between change in QBR when facing extra pressure and how often QBs face additional rushers is just 0.1. In other words, there is almost no relationship at all between how much worse (or better) a guy does when he gets blitzed and how frequently defenses actually blitz him.
Among quarterbacks who have started in 2011, here are the 10 worst against the blitz by QBR: