Tag: Joey Harrington


Evaluating QBs: The Truth Behind QB Records

February 1st, 2013 — 1:08am

*UPDATE: I’ve temporarily changed the blog theme so that the tables in this post will be sortable and searchable.*

With the tedious boring stuff out of the way (if you missed the boring parts, here is boring part 1 and part 2), it’s time for the payoff. I’ll post some results and comment on some of the more interesting findings.

First, the caveats, the fine print. All games from 2000-2012 are included, regular season is assumed unless otherwise noted. From last post, we defined the “QB of record” for each game; that is instead of the starting QB we’ll use the QB who had the most dropbacks for his team in each game (dropbacks = pass attempts + sacks). Again from the previous posts, we defined different phases of the game, which we’ll measure by Expected Points Added (EPA)–despite having my own expected points model, I decided to borrow Brian Burke’s more well-known EP model for this series. Those phases are defense, special teams and offense; most of the time here we’ll be dividing offense into two parts: QB EPA, which are plays where the QB is the passer or rusher, and Non-QB EPA which is all other offensive plays. While part 1 showed that QBs have control over QB EPA but little to no influence over Non-QB EPA, Defensive EPA, or Special Teams EPA that should not be confused with QBs having all control over QB EPA. While that is heavily influenced by the quarterback, receivers, lineman, running backs, the opposing defense, etc. all have some impact as well on these plays.

With the disclaimers out of the way, let’s dive right in. Continue reading »

1 comment » | descriptive, Evaluating QBs Series, Football, offense versus defense, player evaluation, talent distribution, team evaluation

Evaluating QBs: It’s All About Context

January 31st, 2013 — 12:13am

In part 1 of my Evaluating QBs series, we looked at what makes teams win and which of those things quarterbacks have control over. While wins can be useful to separate quarterbacks, that is only because they are correlated with the underlying factors that explain wins. Once we separate out and control for those factors, QB wins provide no further information.

Now that we have shown that QBs have some control over the plays they are directly involved in but no influence over other facets of the game–defense, special teams, and other offensive plays–we can now look at how many wins we’d expect each player to have based only on what they have control over.

We can get at this two ways: directly and indirectly. The direct way is to look at how often quarterbacks win based on their EPA (again, using Brian Burke’s Expected Points from Advanced NFL Stats). The indirect way is to look at how often quarterbacks win based on the EPA of everything else, what I’ll call “support”. That is, the sum of the EPA of the quarterback’s team defense, special teams, and non-QB offensive EPA. Continue reading »

2 comments » | descriptive, Evaluating QBs Series, Football, offense versus defense, player evaluation, talent distribution, team evaluation

Back to top