The Arizona Baserunning Juggernaut

Since the start of the 2015 season, the Diamondbacks have been easily baseball’s best baserunning team. They’ve been baseball’s best baserunning team in terms of stolen bases, and they’ve been baseball’s best baserunning team in terms of other kinds of advances. Baserunning isn’t one of those components that makes or breaks a roster, given that it’s more peripheral or secondary than anything else, but the longer something like this goes on, the easier it is to recognize.

In this very season, the Diamondbacks are at it again. That’s the second-place Diamondbacks, the wild-card-spot-occupying Diamondbacks. A few years ago, by our numbers, as a team they were 13 runs better than average on the bases. Last season, they were 18 runs better than average. This season, they’ve already been about 12 runs better than average. They didn’t do anything noteworthy on this particular afternoon, but that’s what a team gets for facing Max Scherzer. The team’s still been elite, and they’ve played only 30 games.

It’s one thing to think about being +12 runs. That already seems pretty good, what with how little of the schedule has passed. But, say, why don’t I put this in a league-wide context? Here, develop a greater understanding of where the Diamondbacks’ baserunners stand:

You could argue there are several posts in here. What’s going on with the Red Sox? What’s going on with the Astros? Rest assured, if trends keep up, they’re all going to get their posts. It’s the Diamondbacks in here who are most exceptional. At +11.6 runs, they’ve been better than the second- and third-best teams, combined. It’s not just a matter of having a lead. It’s a matter of lapping the competition.

You might be familiar with our three baserunning components. They’re listed on our leaderboards as UBR, wGDP, and wSB. That’s a whole lot of letters, and calculating baserunning value really is fairly complicated. But, in general, the first acronym refers to a stat that measures baserunning events outside of steals. The second one considers double-play frequency, and, at last, the third one addresses steals and attempted-steal failures. Right now, by UBR, the Diamondbacks sit at No. 1. By wGDP, they also sit at No. 1. By wSB, they sit at No. 2, behind only the Reds. No other team is in the top five in all three categories. No other team is in the top ten in all three categories. The Diamondbacks have been peaches, and they’ve been peaches at everything.

It’s not like the Diamondbacks being good here is crazy, since they were already good in each of the previous two seasons. But then, over the winter, they did lose Jean Segura. The team overall has not lost a step. As I sort the leaderboards, the Diamondbacks have three players in the top 20 in baserunning value — Paul Goldschmidt, Jake Lamb, and rather inexplicably Yasmany Tomas. That doesn’t capture everything, because A.J. Pollock is second in baseball in steals. Chris Owings is tied for third. (One of the players he’s tied with is Goldschmidt.)

It’s possible to break down how we’ve gotten here. You already understand the overall numbers. Where have they come from, specifically? For one thing, the Diamondbacks have grounded into a double play in just 7% of their opportunities. That’s the very lowest rate in baseball, where the average is 11%. So far, that’s already seven double plays avoided. Moving on, the Diamondbacks are just 11th in stolen-base success rate, but they’re easily tops in stolen-base attempt rate. As a team, they’ve tried to steal in 12% of their chances. That’s more than twice as high as the average rate, and there’s only one other team in double digits.

Finally, Baseball-Reference tracks something called Outs On Bases (OOB). It measures exactly what it says, excepting stolen bases and pick-offs (which are broken out into their own categories). These are outs on other sorts of events. The Astros have already run into 16. The Red Sox have already run into 14. The average team has run into eight. The Diamondbacks have run into just four. That’s tied for the second-lowest total. This isn’t a function of the Diamondbacks not taking chances; they’ve been reasonably aggressive. They’ve just been successful when they’ve gone for it. They’ve made one out at first, one out at third, and two outs at home. The Marlins have somehow already been thrown out seven times at home. The Diamondbacks, as a team, are tied for as many outs on the bases with Dexter Fowler and Chase Headley.

To repeat a couple numbers, the Diamondbacks are at +11.6 baserunning runs, through 30 games. It’s easy to calculate that that would put them on pace for a season’s-end total of +62.6. It’s also easy to declare that won’t happen, because this data point is too extreme. There are going to be more mistakes, or, if not, there are going to be more unlucky breaks. This pace can’t sustain. But, we have baserunning data stretching back to 2002. Since then, just 13 teams have reached the +20 mark, and just one team has exceeded +25 — the 2010 Rays, who finished at an astonishing +37.6. That team was far and away the best group of baserunners in recent memory, and these Diamondbacks have a long, long way to go before they can enter the same conversation.

But, damned if they’re not trying. The Diamondbacks finished April at +11.0 runs. The 2010 Rays finished their best single month at +9.7 runs. The thing those Rays did was keep it up. The Diamondbacks haven’t yet been by far the best baserunning team for six months. They’ve been by far the best baserunning team for one month and change. It is, if nothing else, a start.