Professional basketball in the U.S. certainly stands out as the sport where skill plays the largest role in shaping results. One intriguing explanation for the NBA’s strong skill contribution is the height of the players. In most sports, the most skillful players within a wide range of heights can make it to the pros. But a relatively small percentage of the population is tall enough to play in the NBA. In their book, The Wages of Wins, David Berri, Martin Schmidt, and Stacey Brook note that only about 3 percent of the male population in America is 6’ 3" or taller, and a tiny percentage is above 6’ 10" (about four standard deviations from the average). Yet almost 30 percent of NBA players are at least 6’ 10". They conclude that a "short supply of tall people" contribute to the talent disparity and hence the greater relative role of skill. The right tail of the height distribution does not overlap completely with the right tail of the skill distribution.

Parcells' "Planet Theory" - there are only so many men on the planet big and athletic enough to play defensive lineman in the NFL

I read the article that the first comment is from about a year ago. When I read it I remember thinking that’s a really good reason why football is the best sport. Football has the best athletes. Unlike basketball which is limited to a very small portion of the population because of height, football can draw players from virtually the entire population. We should expect football players to be much better athletes overall.

I’ve also been thinking about Dallas’s defense and why it’s so bad. In general, I keep coming back to the defensive line, and it was in that context that I started thinking about the first comment again. Specifically, how big does one need to be to play DL in the NFL. Because while Parcells is correct that there are only so many very large very athletic men on the planet there are magnitudes more modestly smaller very athletic men on the planet.

Let’s me give you an example using height as a proxy for size. Height in the US is normally distributed. Mean height for men is 5’9" (69 inches) with a standard deviation of 3 inches. From the normal curve we know that 95.45% of the population is within 2 standard deviations of the mean (between 5’3" and 6’3") and that 4.55% is above or below. Ergo half of the 4.55% is below 5’3" and half is above 6’3", so the subset of men that is 6’3" and above is 2.27% of the population. In graphical terms you’re looking at the little blue shaded area.

via img407.imageshack.us

Let’s look at a wider range of heights. Let’s say that instead of 6’3" you want the population of men who are 6’ and taller. 15.9% of the population meets that criterion. That subset is seven times larger. Here it is in graphical terms.

via img405.imageshack.us

And finally, let’s say you’re looking at the population that is 5’9" and taller. Now you’re up to this

via img713.imageshack.us

A picture’s worth a thousand words right? The implications are obvious. If you’re looking for elite athleticism, it’s preferable to be able to look in the 3nd pool because you have 20 times as many candidates to choose from. That makes it far more likely that you’ll find what you want. So that leads to the key question: how important is size? when you’re looking for DL do you have to limit yourself to the 1st pool or can you look at the larger pool?

With basketball it’s obvious that height really does help. A basketball rim is 10 feet high. But I don’t think it’s clear that weighing more translates into better football performance. For example, I struggle to believe the idea Justin Tuck wouldn’t hold up as a 3-4 DE. Tuck is 275 lbs with no body fat. Compare Tuck with Shaun Ellis on the Jets who’s been probably the 2nd most dynamic 3-4 DE behind Seymour and is 290 with I’ll guess 13% body fat.

Justin Tuck	Shaun Ellis

Does anyone really believe that going from say 8% body fat to 13% would make Tuck a better player? That he’d be able to hold up better? I see Tuck outplaying Canty in New York but some people will say ‘if you put Tuck and Canty on Dallas and Canty is the better player because Canty can hold up and Tuck can’t’. I struggle with the logic.

Let me be clear. I don’t think size is irrelevant. On the contrary I realize its importance. A 300 lb DL with a 40 inch vertical jump is better than a 250 lb DL with a 40 inch vertical jump. There’s prototypical size and prototypical athleticism. And no free lunches. There’s a trade-off. The question is getting the balance between size and athleticism right. Are NFL teams getting the balance between size and athleticism right? (and actually the 300 lber in that example is both bigger and the better athlete … it’s harder to launch 300 lbs straight up than 250 lbs).

Now I’m going to stipulate up front that for this post I haven’t undertaken a rigorous statistical analysis. In an ideal world, I’d look at the key variables (height, weight, athletic markets) and run a regression against draft position and career production isolating the importance of size as a variable. I haven’t done that. But my hunch is that size is being overrated. That’s a long way of saying take this commentary with a grain of salt because they’re anecdotal examples. But here are a few observations to consider.

Observation #1: Jimmy Johnson

The idea that size is overrated is one that most Cowboys fans should find easy to grasp. Why? Part of how Johnson built the Super Bowl teams was by discounting the importance of size. Think of all the players Johnson drafted that didn’t have prototypical size. Emmit Smith, Mark Stepnoski, Tony Tolbert, Darrin Smith, Russell Maryland, Dixon Edwards, Darren Woodson, Zach Thomas, Jason Taylor (later in Miami). It seems like a distinct possibility that part ofJohnson’s draft success was that by discounting size he was expanding the pool of players he was looking at.

He recruited athletes - football talent and size was nice, but speed and athleticism were what he wanted … He took safeties and made them linebackers. He turned linebackers into speedy, edge rushing defensive ends.

Think of integration as an analogy. The schools that integrated first had a huge advantage because they had a larger pool of players to recruit from. Ultimately it forced everyone else to integrate because they couldn’t compete otherwise. If there is a part of the population that can contribute to your success you ignore them at your own risk.

Observation #2: Sack Leaders

Notice anything? That’s right, if you have prototypical size and can play you’re getting drafted in the top 10. However, if you don’t have prototypical size and you can play … you might be an UDFA. So if you want to add the NFL sack leader to your team you have 2 choices. (a) pick in the top 10 or (b) look at guys who don’t have prototypical size (e.g. Cameron Wake: undrafted)

Observation #2: Defensive MVPs

Same point as the sack leaders (Bruce Smith is the exception … Smith was on the smaller size but still went #1 overall). Either pick in top 10 or consider guys who don’t have prototypical size.

Here’s another anecdote. Jason Taylor … too small …

In November 1996, Gary Wichard flew to Ohio to recruit a spindly college linebacker out of the University of Akron who wore No. 33. At first glance, Jason Taylor looked like a safety. Or a receiver. Or a small forward in basketball. But Wichard saw him as an NFL defensive end, even though the kid barely weighed 230.

Observation #3, RB:

OK, I’m getting a little off topic here. Indulge me. Here’s a fun little fact. Did you know that Danny Woodhead was arguably the most efficient RB in the NFL this year? That’s right, check out his efficiency stats. Woodhead lead the league in EPA/A, right in front of Jamaal Charles. Football Outsiders has Woodhead as top 5.

1) Arian Foster, Houston Texans: 581 DYAR (371 rushing DYAR, 210 receiving)

2) Jamaal Charles, Kansas City Chiefs: 555 DYAR (405 rushing DYAR, 150 receiving)

3) LeSean McCoy, Philadelphia Eagles: 401 DYAR (223 rushing DYAR, 178 receiving)

4) BenJarvus Green-Ellis, New England Patriots: 385 DYAR (354 rushing DYAR, 31 receiving)

5) Danny Woodhead, New England Patriots: 341 DYAR (185 rushing DYAR, 156 receiving DYAR)

This is a RB who was cut by the NYJ. What does that say about the NFL talent evaluation process? Really if you saw Hard Knocks you know: the NFL (at least Rex Ryan) loves big guys who can hit. John Connor … the Terminator is a roster lock … but not Woodhead. But are we sure that the ability make big hits translates into wins? I’m not.

Sproles is in the same category … drafted 130th … significantly more efficient than Ryan Matthews this year.

If you’re a NFL GM it makes a lot of sense to be looking for the next Woodhead/Sproles (all those Chris Rainey, Will Demps, McCaleb type guys). Why? Because the normal curve tells us that they’re out there. You’re probably 10 times more likely to find the next Sproles than the next Ngata. And they’re cheap.

Observation #4. Marcus Spears vs. Justin Tuck and Anthony Spencer vs. Lamarr Woodley.

Here’s a painful one for Cowboy’s fans. 2005: Dallas is switching to the 3-4 and need to draft DL. Here are the profiles for 2 potential defensive ends.

Now remember that vertical jump and short shuttle are the 2 key athletic markers for pass rushers. Ok, Tuck is obviously the better prospect, right? What about production on the field?

Marcus Spears’ last year in college

Ranked second in the SEC with 9 sacks to go with 17 tackles for losses ... The 9 sacks ranks as the 4th-highest total in school history … Had a total of 49 tackles

Justin Tuck’s last year in college.

Played in all 12 games at defensive end, earning 10 starting assignments ... finished the season with 73 tackles (43 solos) to rank third on the team ... led the Irish with a school-record 13.5 sacks (106 yards) and 19 tackles for loss (117 yards)

Hmm, Tuck was more productive on the field and was a better athlete, what could explain why Spears was drafted 20th and Tuck was drafted 74th? Truthfully, I don’t know. Knowing what I know about Spears and Tuck (and knowing their statistics) I have a hard time believing it was the game tape. From what I know about NFL coaches here’s my hunch: 307 vs. 265.

It's Parcells' "Planet Theory" - i.e. there are only so many men on the planet big and athletic enough to play defensive lineman in the NFL. To some extent, that theory also applies to the linebackers in a 2-gap 3-4 scheme. Guys like Dat Nguyen sometimes won Parcells over, but he wasted no time in drafting bigger players with a little less speed like Bradie James and Bobby Carpenter and Kevin Burnett to replace smaller players like Dexter Coakley.

Parcells (and the NFL in general) wanted to horde up on ‘planet theory’ defensive linemen(an oh yes, don't forget that Carpenter was a 'bigger' LB). I suspect in 2005 they were happy to trade size for speed. I don’t know if that’s true but if it was, I think it was dead wrong. I haven’t seen Tuck struggle taking on 300 lb OL. Here’s the scouting report on Tuck.

Tuck is the most complete of the Giants ends – effective vs. the run and the pass. Tuck is strong and quick off the ball and capable of playing end or tackle at a high level

Now I admit, I’m cherry picking the evidence a little bit. Tuck was the best lineman from that year. So let’s look at another example. Fast forward to 2007. Dallas is looking for an OLB to pair with Demarcus Ware. Here are two prospects

Again, it wasn’t an on field production issue. It was Woodley not Spencer who led the Big Ten in sacks in 2007. What was the deciding factor? Again I don’t know. My guess? Woodley was short, I really have no other way to explain it. Here’s one take on it. ‘

The 6-1 ½, 266-pound Woodley, who also won the Lombardi and Ted Hendricks awards in college, was nitpicked because of his height and speed. He was supposedly too small to play defensive end and too slow to play outside linebacker.

Woodley had better on field production and better athletic markers but Dallas preferred Spencer. Why? We can only guess. But it’s not like Woodley was unknown. Woodley was literally the next OLB taken in the 2007 draft after Spencer.

Now think about that. What do you think the defense would look like if Dallas swapped Tuck for Spears and Woodley for Spencer?

Bonus for people concerned about the offensive line.From Don Banks 2010 re-draft .. the #4 re-do pick Roger Saffold.

The Redskins have been very happy with Williams' rookie season, and he has more than held his own at left tackle against a steady stream of some of the best pass rushers in the league. But Saffold, who went No. 33 overall to St. Louis, leading off the second round, has been one of the major surprises in the Class of 2010, and he's considered the consensus top rookie tackle by league personnel men. The 6-foot-4 Saffold wasn't thought tall enough to play left tackle in the NFL, but he quickly disproved that, starting from day one for the Rams and superbly protecting Bradford's blind side (just two sacks allowed this season).

Observation #5: Greg Easterbrooks All-Unwanted All-Pro Team

Greg Easterbrook did an interesting feature about the best players who were unwanted (either undrafted or released). It’s an interesting list, All-Pro players that were unwanted. But there’s something else about the list that’s interesting, something the players have in common other than just being unwanted. I’m sure you’ve guessed .. but if not take a look at the table below.

*All height/weight data from Pro Football Reference, I believe these are college weights

Yep, the All-Unwanted All-Pro team is on the decidedly short and small side (by NFL standards).

Observation #6: QBs

Here’s some legitimate statistical analysis from Stumbling on wins. This research only looked at quarterbacks. Here are the findings.

Although college performance impacts draft position, it’s not the factor that dominates this decision. The NFL Combine factors actually explain more of the variation in a quarterback’s draft position.32 Looking at the individual Combine measures reveals that each additional inch in height will improve a quarterback’s draft position by more than one round.

The next step in the analysis is to connect the factors that get a player drafted to what that he does in the NFL. Unfortunately, that step doesn’t meet with any success. Specifically, Wonderlic scores, 40-yard dash times, height, BMI, a quarterback’s production in college (measured via Wins Produced, WP100, or the NFL’s Quarterback Rating), and where a quarterback played in college generally are unrelated to future NFL performance.It appears that all the factors that explain where a quarterback is taken in the draft fail to predict how well he will play in the NFL.

Let’s slightly amend that statement. One can look at individual stats and find something. Completion percentage in college is related to completion percentage in the NFL, although the explanatory power is relatively low. Although college completion percentage tells us something about NFL performance, it doesn’t tell us much about draft position. In other words, completion percentage doesn’t appear to be something on which people focus on draft day.

So at least with QB’s we see that NFL teams overrate height. Taller QB’s are drafted higher even though there’s no relationship between height and performance. In a league that’s had Drew Brees and Joe Montana you’d think there wouldn’t be a huge premium on QB height, but there is. This at least shows that in respect to QBs the NFL is overrating size.

Salary Cap Implications

I could go on and on about this. I won’t. I will mention the other key factor: in the salary cap NFL finding undervalued assets is how you win.

In the pre-salary cap days the key was assembling the most talented team. Assume for a minute that salaries correctly reflected performance (e.g. $1M salary got you a $1M of performance). If a team drafted well they ended up with $100M of salaries and performance while the team that didn’t draft well ended up with $50M of salaries and performance. The $100M team beats the $50M team.

But the salary cap and free agency changed that. The key is no longer finding the most talented players, it’s finding the most undervalued players. A player that you can pay $1M but produces $1.5M of performance. You build a whole team like that then even though both teams have team salaries of $100M, one team produces $100M of performance while the other team gets $150M of performance. The $150M of performance beats $100M of performance.

And who is undervalued? Well Danny Woodhead for sure. He’s getting $400K. Compare that to the Barbarian’s $4M salary and you start to see how you can build $150M of performance for $100M of salary.

This is the dynamic that I see most frequently disregarded. The calls for Ngata and Mankins ignore the key fact: they’re not undervalued. In fact if you’re competing in an auction they’ll probably be overvalued (e.g. Albert Hanyesworth). That’s why I’m wary of high profile free agents. If you’re looking for undervalued players I think you’re more likely to find them if you’re focused on finding the next Cameron Wake ($1M / yr - UDFA) or Danny Woodhead ($400K – UDFA) instead of the next Ndamukong Suh ($12M/ / #2 overall).

Conclusion

A preference for bigger players is the same as a prejudice against smaller players, it’s the other side of the same coin. And that's why I recoil when I see a reflexive discounting of smaller players. Prejudice is always a sub-optimal strategy, just look at how segregated teams fared against desegregated teams. The goal is to be unbiased, to have neither a preference or a prejudice, to be able to recognize players, big or small, that can help your team.