"The Blind Side:" I still can't figure out why left tackles are so valuable
Yesterday, Steven Levitt recapped "The Blind Side" over at his Freakonomics Blog. Levitt points out that while quarterbacks are the highest paid NFL players, at about $5 million per year, left tackles are second, at $4 million. He writes,
"The book highlights how N.F.L. teams only slowly became aware of the immensely important role that offensive left tackles play in protecting the quarterback from blind-side hits."
But I still have a problem with this idea of Lewis's, that left tackles are so valuable because they save the quarterback from injury. How many quarterbacks get injured? Say, 25% a season? (That seems high to me, but let's give the left tackles the benefit of the doubt.)
And of those 25%, how many were injured because of a blind-side hit that the left tackle could have prevented? Again, let's say 25%.
25% of 25% is about 6%, so about one quarterback in 16 can be saved by the left tackle.
But, now, what's the difference between a typical left tackle and the replacement-level left-tackle? Let's suppose the average left tackle is twice as good as preventing QB injury as the backup. That means that the good LT could save only 3% of the quarterbacks under his care.
Now, 3% of a $5 million quarterback is only $150,000. (Of course, some injured QBs are out more than one season, so you'd have to multiply the $150K by the number of seasons. But many injuries are for only a few games, so it seems reasonable to figure one year as the average.)
So how can you argue that the LT is worth $4 million because of only $150,000 in quarterbacks saved? Obviously, if left tackles deserve to be the second-best paid position in the NFL, they must be doing something else right.
Maybe it's sacks. But as I wrote two years ago,
"The Hidden Game of Football" (p. 104) estimates that the difference between a good quarterback and an average one is four completions per game. An eyeballing of 2005 NFL sack statistics shows that the difference between a good individual sack total and an average one is only about four sacks per *season*. That’s a difference of 1500 percent in favor of the quarterback."
So if a good QB is worth $5 million a year for those 60 extra completions, then a good LT should be worth only about $350,000 more for those 4 saved sacks.
So $150,000 in injuries saved plus $350,000 in sacks prevented adds up to only $500,000. Where's the other $3.5 million?
Well, there's also the unmeasured effect of giving the QB more time in the pocket. But that would have to be huge, wouldn't it, to add up to $3.5 million? You'd need the LT to be responsible for 2 or 3 extra completions per game (or the equivalent in yards). That seems unlikely, considering that the rest of the offensive line has a big stake in the outcome as well.
The bottom line is: I can't really figure out why left tackles are considered as valuable as they are.
One possibility: the famous career-ending injury to Joe Theismann came from the blind side. Could that gruesome example of what can happen to a blind-sided quarterback have caused GMs to overestimate the value of the left tackle's job?
(UPDATE: "Doc" points out in the comments that it's not the full $4MM we have to explain, just the premium above other offensive linemen. He's right. That premium appears to be only $1MM or so. So it's $1 million we have to explain, not $4 million. But, still, it's hard to see how that million dollars is just for the value of protecting the QB from injury. It seems more likely that only a small portion of that has to do with injury, and the rest has to do with LT being the most important blocking position, and teams putting their best lineman there.)