2014 NFL Draft: Comparing Running Backs using Z-Speed Score and Punch Score

Casey Sapio-USA TODAY Sports

Charting running backs of past, present, and future to find a correlation with success.

Time for some fun, interactive graphs. We don't do this enough and it's a point of emphasis to do this sort of thing more often. Huge hat tip to John Crean for all his help in getting this going.

Punch Score vs. Z-Speed Score

The chart below plots Punch Score as a function of Z-Speed Score. All players who participated in the 40–yard dash, Bench Press, and Broad Jump since 1999 are plotted in yellow or red, depending on whether they accumulated any value in the NFL or not. Additionally, the player's average Career Approximate Value — a measure of a player's value derived by Pro Football Reference — dictates the size of the player bubble. A bigger bubble means the player had a greater career value.

The running backs eligible for the 2014 NFL Draft are plotted with blue bubbles, with a fixed bubble size so you can easily see the player, but not have it dominate the graph.

As I mentioned, these are interactive. If you hover your mouse over the chart, you'll be able to see dwietails of who's represented by that bubble. You can turn plots off and on by clicking their series name in the legend. You can also zoom in to the chart by clicking–and–dragging over the area you want to zoom in on. You could also print the chart in case you need to test your printer or something.

For reference, I have included the player's draft information in the tooltip that appears when hovering over a point, or his college if he's a potential 2014 selection.

Okay, so there is some bias in this chart. Since it's an average, it's not necessarily accurate for younger players. For example, all of Alfred Morris, Doug Martin, and Giovani Bernard have huge bubbles that could easily deflate with one off–year. Additionally, players who retire early are penalized, as everyone who has spent at least eight years in the NFL has exactly 8 years treated as the divisor. This is to give players who play longer more value in this chart while giving it a realistic expectation of good service.

Here's my take from this: it's almost as if the graph is tilted. That is, if you drew the line y = -x + 0.5 over the chart, the players "to the right" of the line are vastly more likely to succeed than those to the left.

2014 Class Analysis

The Good Ones

There are a handful of backs who land favorably in the Z-Speed Score / Punch Score plane. Notably, Bishop Sankey fits right in the Zac Stacy/Ray Rice mold. Henry Josey and Ladarius Perkins are right around that zone, too, which may signal they're steals waiting to happen at their current projected draft position of Undrafted.

Crowell, Atkinson, and Sims are all on the positive side of the Z-Speed Score, but negative on the Punch Score side. They're still in good company, though, so I don't see a reason to significantly alter their draft stock any more or less than you would based on their colloquial speed score.

Then, there's workout warrior Jerick McKinnon. His combination of Z-Speed Score and Punch Score are literally off the charts. In fact, there isn't a higher Punch Score to–date for a player who also participated in the Broad Jump (so whose foot speed we can examine in the next post). I think he makes a worthy gamble, provided his foot speed isn't horrific.

The Bad Ones

DeAnthony Thomas. A lot of people don't think he'd cut it as a running back, and I find it very hard to disagree with that based on his measurables. He's deep in the "this guy is worth nothing" territory, and it seems foolish-to-stubborn to think he'll be anything but a disappointment. Oregon doesn't have the greatest track record of turning their collegiate running backs into stars at the NFL level anyway — backs like Barner, James, and Blount don't really scream "cream of the crop" — so it isn't as if he's got some system intangible that we can definitively say will translate to the pros.

The guy projected by some as the #1 RB on the board, Ka'Deem Carey, plots poorly here. For a guy with such a negative Z-Speed Score, you'd hope he'd have a lot of upper body mass to explain his weight. He doesn't, or at least you can't tell by his bench relative to his peers. He makes an interesting test case, but seems like a reasonable bet to be a bust. This isn't something that Punch Score itself diagnoses, though, as his ordinary Speed Score would tell you that too. Punch Score, though, confirms he isn't Brian Westbrook or Darren Sproles in terms of player archetype that may explain his poor Speed Score.

A handful of high Z-Speed Score players are well into the negative Punch Score territory. While this territory isn't a wasteland, it's not in the positive-positive quadrant where there's a great bet the player will succeed. Here, the negative Punch Score should temper the optimism that would ordinarily come out of the player's Speed Score.


In my next post, I'll plot the same thing, except against Foot Speed. I'll also include a wrap-up on the position's potential steals and busts.

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