MLB

No matter how you spin it, some guys are faster than others. Newly released data from MLB’s Statcast give us a new depth of insight into just how quickly one can get from A to B, and just how much that matters. (It does; it’s not all that does.)

Even as the game moves further and further away from small ball, the arts of scoring from first on a double or keeping a rally alive by thwarting an attempt at a double play remain essential and exciting. Speed, though, has been difficult to quantify; analysts have been able to measure the value of baserunning, but that’s about it.

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MLB calls its new statistic “Sprint Speed,” which identifies a runner’s speed at a measurement of feet per second. (The statistic doesn’t use miles per hour because it’s a bit silly to measure the time it takes for a runner to cover 90 to 360 feet on that scale.) Specifically, the number given for each runner is the fastest second at which they were measured while at a full sprint on the base paths, giving you an ultra-optimized portrait of their top speed.

Using sprint speed data from the 2016 and 2017 seasons provided by MLB.com—who published all of their data from the metric on Baseball Savant Tuesday—we compared measured speed to existing baserunning metrics, as published by FanGraphs, which has two baserunning statistics: Baserunning (BsR) and Ultimate Baserunning (UBR). You can read the full explanation for the statistics here and here, but basically UBR measures baserunning value without stolen bases—instinct and success in opportunities such as tagging up or stretching a single into a double—while BsR uses UBR, weighted stolen bases, and weighted GDIPs to give you something like a WAR for baserunning.

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Using sprint speed, we can identify a range of mismatches between pure speed ability and success as a baserunner. Some guys who are particularly speedy may not know how—or be put in positions in which—to use it, while some guys manage to make more of less.

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BsR is an accumulative instead of a rate statistic, so we decided to stabilize the numbers a bit by using BsR/PA to weigh against sprint stat. Doing so helps create a common denominator across the league, and as it turns out, speediness really is just about as important as we thought it was.

Because BsR and UBR are best measured over the course of a season to begin with, we started with 2016 for players with at least 200 plate appearances.

BsR/PA versus sprint speed for the 2016 season:

(Full chart with labels—albeit difficult to read labels—here.)

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This confirms what we knew: Billy Hamilton was the fastest and most valuable overall baserunner in baseball last year, and Billy Butler was the least valuable (though not slowest). The chart also shows us that Hamilton did more with less speed than Byron Buxton, and that Butler did a lot less with a lot more speed than old men Albert Pujols and Brian McCann.

José Ramírez also acquitted himself quite well despite having just above average speed, and Hunter Pence’s reputation as a guy who uses his speed to run himself into trouble more often than not is well-earned.

To give a sense of the differences here, sprint speed indicates that at their fastest Buxton could run four bases in the time it’d take McCann to run three.

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In 2016, the correlation coefficient between sprint speed and BsR/PA was .66, establishing what we already knew through common sense: Speed is highly but imperfectly correlated with successful baserunning. The two are distinct.

UBR/PA versus sprint speed for 2016:

(Full chart with labels here.)

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This chart brings some clarity with regards to who most derives their value as a baserunner from their ability to steal bases. Hamilton’s drop is obvious and expected, but Pujols’s is a bit more surprising. And look at José Ramírez up there, still in a strong outlier position. Without the benefit of stolen bases and getting out of double plays, Jett Bandy was the worst baserunner in the league—a title ill-suited for a man named Jett.

We’re not really far enough into the 2017 season to have definitive data, but here’s how things stand so far for players with at least 200 plate appearances.

BsR/PA versus sprint speed for 2017:

(Full chart with labels here.)

UBR/PA versus sprint speed for 2017:

(Full chart with labels here.)

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So far it looks like sprint speed will confirm what is easily recognized anecdotally and imprecisely, and it has a zippy name to boot.

It’s valuable to have a concrete visualization of how pure speed correlates to baserunning value, and satisfying to see certain reputations confirmed by the data. Guys like Pujols and Paul Goldschmidt have always been considered canny baserunners who positively affect the game despite not having elite speed, and the charts bear that out. The same goes for players like Pence and Yasiel Puig, whose escapades on the basepaths are often maddening and counterproductive.

Using sprint speed we can know just how unlikely Billy Butler’s steal in the 2014 ALDS was, and appreciate all the young, speedy, talented baserunners like Mookie Betts, Trea Turner, Billy Hamilton, and Byron Buxton we get to watch right now. Which is a good thing to do: Speed gets taken for granted until you really, really need it.