Stevan Ridley, the NFL, and fumbling rates

The Harvard Sports Group posted an interesting tweet this evening

This brings up an few points with respect to fumble risk and fumble luck among NFL ball- carriers. The overall numbers indicate that the Patriots running back of choice against the Texans, Blount, actually may have a higher likelihood of fumbling that Ridley. Of course, the inherent problem in using their career numbers is that they may not accurately indicate which back is more likely to fumble going forward. Specifically, Ridley has three fumbles in his last three games.

How do Blount and Ridley’s career compare?

To compare the career arcs of Blount and Ridley, I started by making a list of the number of touches (runs or receptions) each player has had in between fumbles in his career. Ridley, for example, went 93 touches before his first fumble, and then another 9 before his second, etc…

Ridley: 93, 9, 78, 29, 125, 24, 72, 10, 96, 23, 8.

Blount: 33, 98, 26, 29, 93, 47, 8, 22, 8, 60, 99, 42

Ridley’s 3 fumbles in his last 32 touches aren’t nearly as bad as Blount’s worst slump, which occurred in mid-2011.  At that point, the then-Buccaneer Blount fumbled 4 times in 38 touches in games against Tennessee and Jacksonville.

However, Blount has fumbled just twice since that Jacksonville game, a span of roughly 30 games. Safe to say that if the Patriots believe that fumbling is a pattern or a habit which is tough to get rid of, Blount is the safer option.

Collegiate performance:

I counted Blount with 2 fumbles in 158 touches at Oregon, while Ridley fumbled 3 times in 323 touches for LSU. No difference there.

How does this compare to the rest of the league?

NFL backs fumble roughly once every 90 carries. So by comparison, Ridley and Blount are both worse than the league average.

Can these two running backs change their fumble rates?

Which Patriots running back from LSU was also well below the league average? Kevin Faulk, who Bill Belichick once called “an inspiration to all of us.”

Faulk fumbled 20 times in 1295 career touches (1 every 65), but started his career with 9 fumbles in his first 294 chances during his first two seasons with the Patriots (1 every 32). By 2006, Faulk had the fumbling thing more or less figured out, as in his final 6 seasons, the third-down back fumbled just once in 455 touches.

Fumble recovery rates

Of course, hidden behind many decisions are variables that coaches, or fans, haven’t thought of. For example, Ridley’s fumble problem of late has been compounded by the fact that he, and his teammates, have not been able to recover the loose ball. Fumble recovery rate is a huge luck-factor across the league and in Patriots games in particular, which I brought up in a blog post last year.

While the Patriots recovered three of Ridley’s first five career fumbles, six consecutive Ridley fumbles have been recovered by opponents. The league average recovery rate on non-QB runs is about 60%, according to this post by Chase Stuart, so in some sense, Ridley’s been unlucky of late.

What’s left to do?

For starters, Kevin Faulk is just one player, so it’d be interesting to identify if league-wide, fumble rates tend to stick or vary over the course of players’ careers.

I think a more interesting idea might be whether or not coaches overreact to lost fumbles, as Belichick may be doing with Ridley. If Logan Mankins had pounced on two of Ridley’s recent three fumbles, would he still have been benched?