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The 2016 Arizona Diamondbacks are running wild

There’s one area this team is the best it has ever been. That’s on the base-paths.

MLB: Houston Astros at Arizona Diamondbacks Mark J. Rebilas-USA TODAY Sports

We should start with a quick discussion of BsR, the metric we’ll be using to look at how Arizona has performed on the bases. It’s a little more nuanced than simply counting up stolen-bases, because there’s more to base-running than that. Other aspects include going first-to-third on a single, taking bases on a sacrifice fly, advancing on wild pitches and passed-balls, and not hitting into double-plays because you legged it up the first-base line quickly enough. All these factors are taken into account in BsR; if you want more details, here’s the Fangraphs page that talks about it in more details. For everyone else? Just know it measures how many runs a player/team gains or loses, as a result of their base-running.

It seems to be an area where the arrival of Dave McKay as first-base coach has had a huge impact on the team. For in the season before he arrived (2013), the Diamondbacks were awful: their BsR was -18.8 runs, which ranked then 29th in the majors, ahead only of the Tigers. Their success rate at stealing bases was an MLB worst, at only 60%, well below the break-even point. But since McKay took over from Steve Sax, there has been a steady increase in the team’s productivity, as measured by BsR.

  • 2013: -18.8 (29th)
  • 2014: +1.0 (14th)
  • 2015: +13.2 (3rd)
  • 2016: +20.7 (2nd)

That’s an improvement of close to forty runs over three years. Since the start of the 2015 campaign, the Arizona total of +33.9 runs gained by their base-running is the most in the majors, over four runs better than the next-placed Cubs. The change in all areas has been startling, but perhaps nowhere more so than in the area of straight bag thievery.

In 2013, Paul Goldschmidt led the team with 15 stolen-bases. This year, he has close to twice as many, with Jean Segura (31) and Chris Owings (20) also surpassing 2013’s best - and there’s little doubt a full season of A.J. Pollock would have done so too, since he stole four in only 12 games. Equally impressive as the sheer number is the success rate: Goldie, Jean and CO have combined to steal 80 bases while being caught only 16 times. The top three in 2013 (Goldie, Pollock and Gerardo Parra) stole less than half as many, 37 bases, but were still caught more often (20). All told, in three years Arizona has doubled its SB, going from 62 to 130, while being caught less, dropping from 41 down to 30 tiimes.

Not all of this may necessarily be down to McKay, since the Diamondbacks are a younger team than they were three years ago. In 2013, the average age of their position players was 27.6 years old, with thirty-somethings like Cody Ross, Jason Kubel and Eric Chavez, not exactly speedsters, all getting 250+ PA. This season, Michael Bourn is the sole equivalent, and even he stole 13 bases in 18 attempts before his departure for Baltimore. Indeed, there’s only one player on the entire roster this year to have a SB% of below 70%; Yasmany Tomas, who has been caught four times in his six attempts. As we’ll see, base-running is one of the factors that helps negate Tomas’s offensive production.

That 81% stolen-base success rate is the best in the National League, but the team has also been better than average in other areas. They have taken an extra base e.g. going first to third on a single, 43% of the time, the third highest rate in the NL. Yet this has also not resulted in more outs on the base-paths; at 49, Arizona has four fewest TOOTBLANs in the league. Perhaps surprisingly, even "Windmill Williams" deserves some credit, for the number of runners the Diamondbacks have had thrown out at home is also well below most, at 12 compared to a league average of 17. The only area where more work might be needed is pick-offs: we’ve been the victim 14 times there, two more than average.

So, who’s the best runner on the team? In BsR terms, the answer is Goldschmidt, +5.0 runs above average. Segura and Lamb are second and third. At the other end of the spectrum, Welington Castillo is second-worst, at -2.2, though you don’t expect catchers to do much. The best-running catcher this season, at +2.1 BsR is... Chris Herrmann; he and the RockiesTony Wolters are the only ones worth more than +2, and of the 68 catchers with 100+ PA, all but eleven are at or below zero. Far worse than Castillo, however, is Tomas, who is -4.6 this season, and more than eight runs below average since the beginning of last year. So it’s not just his obvious defensive range which hampers his overall value to the team. What’s Dave McKay doing this winter?

But as well as BsR, we should look at the number of times a player was on-base; as Billy Hamilton shows, you can’t steal first. Goldschmidt not only has most PA on the team, he also gets on base at the best rate, giving him the best chance to put up a high raw BsR number. To figure out who is the "best" base-runner, I took PA and multiplied that by OBP, to get an idea of the number of times they were on base. [Yes, I know this will exclude errors, times they reached on a fielder’s choice, etc] I then worked out the BsR per 100 times on base, to give me a figure that roughly also takes playing time and on-base skills into account. The chart below shows all D-backs with more than 60 PAs this season.

Name PA OBP BsR BsR/100OB
Chris Herrmann 166 .352 2.1 3.59
Phil Gosselin 236 .325 2.6 3.39
David Peralta 183 .295 1.6 2.96
Chris Owings 451 .318 3.6 2.51
Jake Lamb 578 .330 4.3 2.25
Socrates Brito 90 .200 0.4 2.22
Michael Bourn 358 .307 2.2 2.00
Tuffy Gosewisch 92 .228 0.4 1.91
Jean Segura 679 .366 4.5 1.81
Paul Goldschmidt 689 .413 5.0 1.76
Rickie Weeks Jr. 205 .327 1.1 1.64
Nick Ahmed 308 .265 0.9 1.10
Mitch Haniger 108 .296 0.2 0.63
Peter O'Brien 66 .182 -0.1 -0.83
Brandon Drury 484 .322 -2.2 -1.41
Welington Castillo 453 .322 -2.4 -1.65
Yasmany Tomas 555 .312 -4.6 -2.66

Speed obviously helps, with guys we know as fast all being at two or above: David Peralta, Owings, Bourn, Socrates Brito, etc. There is also likely an element of small sample size in some cases - I would be hesitant to claim Tuffy Gosewisch is as good a base-runner as Jean or Goldie! But it’s interesting to see utility guys like Herrmann and Phil Gosselin performing well by this metric. Again, it also shows how many players on the current roster provide a positive contribution from their base-running. While there are many reasons to be critical of the team this year, the work done by Dave McKay - and also the effort from the players - in this area, is one which probably deserves more credit than it has received.

[All stats through the start of play today]