“Good QB” Does Not Mean “Good Fantasy QB”

Title: “Good QB” Does Not Mean “Good Fantasy QB”
Date: August 25, 2009
Original Source: The On Deck Circle
Synopsis: I got really analytic (by my standards – I used regression) in breaking down how strong QB play doesn’t necessarily correlate with strong fantasy performance, and which statistics are the best indicators of fantasy value.

Hey, remember two weeks ago when I said I’d be doing fantasy football position focuses leading up to your draft? It wasn’t a lie, but I’m switching up the format. The last one gave away too much information for free to my league competitors, who all read the site because, well, I’m awesome.

So for today I’m going to focus on a nuance about fantasy football that bothers me a little bit. While not universal, analyzing real football and fantasy football are different beasts. There are things players can do that simply don’t translate to the three or four stats used to accrue points for his position, and nowhere is this more true than at Quarterback (unless you play in an IDP league, in which case you can just ignore me).

Quarterbacks have a strange fantasy history – long considered staples of winning fantasy teams, the RB-RB strategy pushed them down draft boards, and now with the RB point differential shrinking, they are re-entering the conversation as high as the first round. And there is no hiding the studs – everyone wants Peyton Manning, Drew Brees, and Tom Brady. Those who don’t get them will convince themselves to follow one of two strategies: optimistically buy into one of the second tier quarterbacks, self-hyping the player to the level of Tier One (and we see this every year); or gamble on two or three lower-tier quarterbacks while promising to ‘play the match-ups’ or ‘let them compete.’

Regardless, without a clear top-tier quarterback, one can be left rather aimless in terms of quarterback strategy. So today’s article has a tip for you: actual on-field performance or results don’t necessarily translate to fantasy gains.
 More after the jump!
Specifically, I’m referring to the somewhat loose relationship between passer rating and fantasy worth. While the relationship is positive and fairly strong (with fantasy points and QB Rating sharing a correlation of 0.74), it makes my point from the introduction clear – fantasy worth isn’t necessarily a function of real football value.

looked at something similar earlier this month about baseball, wondering if OPS could be used in place of AVG or OBP, so that a fantasy team would better reflect a real team (which is the point, or at least it was the intent of fantasy sports at the time of their creation). With football, there is no clear OPS-like answer. In fact, it’s unclear if QB Rating is even the best statistic for quarterbacks, though it has been a favorite for some time (alas, football is understandably behind in the statistical revolution).

So we’re left with a dilemma whereby what our eyes tell us, what the stats pages tell us, and what we know from Madden on XBox, as a function together, may lead us awry in the search for fantasy points. That is, with an R-squared of 0.55, the stat, QB Rating, only explains about 55% of the variance in fantasy points produced by quarterbacks.

So what’s a girl to do?

Put simply: chase Touchdowns. TDs have a correlation of 0.94 with fantasy points, and an R-squared of 0.86 (TDs explain 86% of the variance in fantasy points). By comparison, Yards Gained only has a correlation of 0.79 with an R-squared of 0.63 (slightly better than QB Rating but nowhere near as good as TDs).

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To further prove my initial point that real success is not the same as fantasy success, Interceptions have a positive correlation of 0.20 with an R-squared 0.04. While these numbers are very small and may be subject to small size bias, nobody would argue that this finding spits in the face of football wisdom – interceptions are, without question, a bad thing. Save the Gunslinger argument, Favre fans, turning the ball over is always bad.

Obviously, there’s no solution to this dilemma – you have to take fantasy quarterbacks for what they’re worth, and draft on fantasy potential instead of real potential (Joe Flacco alert!). Game managers need not apply, gunslingers be the praised, and the Sean Payton Offense rules all.


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