Can solid running backs really be found anywhere in the NFL draft? Years ago the conventional wisdom seemed to be that a team needed a superstar RB from the first round to win consistently. Now it seems that the conventional wisdom is that teams still need a star ball carrier, but one can be found deep in the draft. So which is it?
The data consists of RB draft picks from the 1980 through 2000 drafts found at Pro-Football-Reference.com. Running back career performance was judged three ways. First, I averaged the likelihood a RB would be selected to one or more Pro Bowls by round and draft order. Second, I averaged career Yards Per Carry (YPC) by draft round and by draft order. (I also tried various ways of including receiving yards, but the variance in Yards Per Reception is very large and it distorted the data, particularly for players with relatively few receptions. Ultimately, simple YPC worked best and aligned closest with how most people see RBs. That is, Steve Sowell and Dave Meggit aren't ranked above Barry Sanders, Thurmond Thomas, or Emmit Smith.) And lastly, I averaged the number of years as the primary starter by round and by draft order.
Pro Bowl Selection
Although Pro Bowl selection is a flawed measure of career performance in many ways, it can indicate that a draft pick has "panned-out." If you sort the data by PB selection, it very quickly separates the generally productive RBs from the "three yards and a cloud of dust" guys. After looking at PBs for a number of positions now, it seems that 2 or more PB selections is a particularly good measure of career productivity, especially when judging top draft choices.
The graphs below illustrate the likelihood that a RB will be selected to one or more, two or more, and three or more PBs. The first graph is by draft round, and the second graph is by RB draft order (i.e. 1st RB taken, 2nd RB taken, etc.)
I wouldn't read too much into the spike at the 5th RB taken. It's likely just a statistical quirk, but it might be one reason why many experts believe that later round RBs are as good as early round picks.
[Edit: Some have asked why I brushed off the spike of Pro Bowls at the 5th RB taken as a quirk. If we analyze enough draft picks for various positions, as I'm in the process of doing, we're bound to see a significant bunching like this by chance once or twice. The graph is relatively continuous except in one place, where there is a depressed result at the 4th and 6th pick and the spike at the 5th. What is likely at work is that positive results in the 5th pick "bin" have randomly "stolen" positive results from the 4th and 6th bin. There were 20 RBs taken as the 5th RB in the data set, so it would only take 2 or 3 RBs who would otherwise have been the 4th or 6th pick to be bunched into the 5th pick to give us this result. Unless we had a reason to believe there is some special quality about the 5th RB taken before seeing the results, we should not interpret the data to say there is something magical about being the 5th RB taken.]
Yards Per Carry
There is probably no simpler and truer measure of running back performance than yards per carry. Of course, YPC does not belong to the RB alone. For any one RB's season, offensive line ability has a tremendous influence on his stats. But over 490 careers and over 24 years of data, the abilities of offensive lines will average itself out to a great degree, leaving career YPC a reliable estimate of true RB performance when grouped by round or draft order.
As with QBs, the biggest question is how to score draft picks with no carries or very few carries. RBs with fewer than 200 career carries tended to have extreme YPC stats. I assigned them the YPC of the 5th percentile qualifying RB, which was 3.58.
The two graphs below break out career YPC by draft round and by draft order.
The first round RBs, particularly the first couple taken, tend to significantly outperform later picks. By the 3rd or 4th round and the 7th RB taken, teams are likely getting sub-replacement level special teams fodder.
Also notice the nearly 1:1 relationship between career YPC and PB selections, including the spike at the 5th RB taken. This suggests that PB selection is merit-based and is a reasonable proxy for grading career performance.
How often do the scouts get it right? In other words, how often does the higher pick turn out to be better than the next pick? The two table below lists the likelihood that the higher pick will have a better career YPC than the next RB taken in the same draft. We shouldn't expect the scouts to be perfect, but this table tells us how difficult it is to predict the better player.
Years as Primary Starter
|Round||Yrs as Primary Starter|
|RB Pick||Yrs as Primary Starter|
Top picks solidly outperform subsequent picks. The top two RBs taken tend to almost be in a class to themselves, then there is a steady decline in expected performance until the 8th RB taken, at which point there is very little to be expected from a pick.
So do teams need a superstar #1 pick RB to win, or can they find a premier runner deep in the draft? Which conventional wisdom was right? My theory is it's neither.
I think most people still grade RBs in terms of total yards, whether it's for a single game or for a season. Even though it should be well known now that winning leads to running, rather than vice versa, commentators and analysts continue to count 100 yard games or 1000 yard seasons as measures of RB effectiveness.
But even below-average RBs on winning teams with good passing games and good defenses will tend to accumulate large chunks of total yards due to frequent carries. Even a RB who was a 5th round pick on a great passing team will appear much better than he truly is. I believe that might explain the perception that solid RBs can be found anywhere in the draft.
The better RBs really do come from the top picks. It's just that they're not that important, or at least they're not as important as they were in the 1970s before the NFL became a passing league. Plus, our understanding of which RBs are truly the very good ones is distorted by analysts who insist on total yards as the best measure of RB performance.