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The Diamondbacks on the basepaths

It seems like the team has struggled with their base-running this season, despite firing former first-base coach Eric Young Sr. Is that borne out by the numbers?

Jared Wickerham

Coming into 2013, one of the aims of the Diamondbacks was to improve their performance on the base-paths. Last year, the team's success-rate when stealing bases was only 65%, second-worst in the National League, though their outs on the basepaths and times when they took an extra-base were both close to average. Out went Eric Young Jr, and in came Steve Sax. However, performance has, if anything got worse. Our SB% has dropped to 57%, the worst in franchise history (even the woeful 2004 team were at 62%), and the apparent aggression hadn't translated to taking the extra-bases, with a rate now below-average. Let's go deeper into the numbers so far.

Stealing bases

The most obvious measure of base-running has also been the most problematic. We've been caught stealing 29 times, with only 38 successes: the only team with more failures is the Brewers, but they also have 101 SB to their credit. Gold stars go to A.J. Pollock (8-3) and, perhaps surprisingly, Paul Goldschmidt (11-4). Well, it's only a surprise due to his position: he's the sole 1B in the major-leagues with double-digit steals to date. But then, he led all players at his position last year with 18, which in addition was the most ever by a Diamondback first-baseman, pipping the 17 stolen by Travis Lee in our rookie season of 1998.

At the other end of the spectrum, we have Gerardo Parra (7-9) and Martin Prado (3-5), both well below the rate at which they are helping their team. Parra used to be very good: he went 15-1 just two seasons ago, but since then has regressed to neutral in 2012 (15-9) and positively a liability this year. It's weird, because he has certainly no shortage of raw speed, and just turned 26 in May. With Prado, it's more of a return to normal. From his debut through 2011, he was 13-15 in stolen bases, but suddenly appeared to "get it" last season, being successful 17 times in 21 attempts. This season: not so much.

Taking extra bases

This is a related, but somewhat different skill: going first to third or coming home from second on a single, or scoring all the way from first on a double. It's important to note that there are factors here which aren't within the runner's control. Take Aaron Hill's double in the third last night, which scored Eric Chavez all the way from first. Really, not scoring from first would have been more of an issue there - not all doubles are equal. And if the hit driving Chavez in had been by a fast runner, say Adam Eaton, it could have been a triple, and Eric wouldn't have got any base-running credit. Still as a general measure, these kind of things should even out.

League average is 41%. Arizona comes in just a little below that, at 40%, eighth in the league. We are particularly tentative going first to third on a single. We've done that successfully only 52 times in 216 chances, a 24.1% rate compared to 28.0% league-wide. However, the reverse is true with regard to coming home on a single from second: we've done that 78 times out of 111, a 70.3% rate which is well-ahead of league average, 60.8%. Score one for Matt Williams there, I think.

On the individual level, Didi Gregorius (58%), Parra (49%) and A.J. Pollock (46%) lead the team - Eaton is up there too, but hasn't had a significant number of chances at this point. At the other end, you will not be surprised to find our two catchers, Miguel Montero (24%) and Wil Nieves (27%), with Cody Ross also down there (30%). However, we are likely getting down toward the area of small sample-size. Take Goldschmidt's numbers: he rarely goes first-to-third, only four times in 30, a 13.3% rate which looks pretty bad. Yet, few have been better than Goldzilla at going second-to-home, which he has done all but three of 17 times, an 82.4% rate.


They happen to every team, but outside of the poor stolen-base success-rate, Arizona are actually about normal. Indeed, our 35 outs on the basepaths is a little below average (37), though those don't include caught stealing or pickoffs, which are counted separately, and are areas where the D-backs haven't done so well. Including all those as well, we have 70 TOOTBLANs in total, with the league-average being 67.

Gerardo Parra is seeking to defend the King of the TOOTBLAN crown he claimed last year, with a final tally of 19, half a dozen clear of runner-up Montero. Leading for Arizona so far are... Parra and Martin Prado, each of whom have 12 in total. This season, they find themselves ahead of Cody Ross (8) and Didi Gregorius (7), and that quartet are responsible for more than half the team total between them, with no-one else having more than five to date.

I should discuss Williams more, since his presence at third-base has certainly led to an increased number of outs at home. In 2010, the last year before his appointment, we had only 12, second-fewest in the NL. His first season, 2011, that jumped to 28, tied for most, and 2012 was barely better (25, =3rd). While this season has again shown slight improvement, the pace is still 22, third once more. Curiously, we seem to have a smaller percentage of our TOOTBLANs at third than most teams. Seems our base-runners are perfectly fine running toward Williams, but running past him is lethal.

Base-running measures

There are a couple of stats which attempt to take all these factors and put them into a single number that shows how good (or otherwise) a team is on the basepaths. To explain how these work, you need to be familiar with the idea of the Run Expectancy matrix. However, if you're not interested in peering below the hood and seeing how this works, you can skip ahead to 'The Diamondbacks collectively'. We won't judge you for it...

Runners 0 Outs 1 Out 2 Outs
Empty 0.4692 0.2517 0.0934
1-- 0.8266 0.4983 0.2101
-2- 1.0570 0.6428 0.3079
--3 1.2772 0.8985 0.3584
12- 1.4144 0.8894 0.4246
1-3 1.6346 1.1451 0.4751
-23 1.8650 1.2896 0.5729
123 2.2224 1.5362 0.6896

What this gives you is the expected number of runs which will score in an inning (based on 2013 results), given a certain number of outs and situation on the bases. For example, at the start of an inning, the average number is 0.47 runs. If the lead-off man makes an out, that drop to 0.25 runs. But if he reaches base (and it doesn't matter how), the expected number of runs increases to 0.83.

What does this have to do with base-running? You can use it work out the value of a stolen-base or other action on the bags. Take a situation where you have a guy on first with zero outs: you expect to score 0.83 runs. If he takes off for second and makes it, now you expect to score 1.06 runs - the stolen-base was "worth" 0.23 runs. But if he gets caught, with the bases empty and one out, your run expectation is 0.25 - the failure "cost" you the difference, of 0.58 runs, a lot more. That's why you need to steal at a higher success-rate than 50% for it to be worthwhile, because getting caught hurts a lot more than. The break-even rate with zero outs is about 71%. [Remember, we're at 57%]

You can do similar calculations for everything else that happens on the bases. What was the run expectancy before the base-running action? What was it afterward? Doing so, you can assign a value for everything from going first to third on a single, to getting thrown out at home. Add up those values over the course of a season for a team or player, and you get a number which shows how many runs a player added or subtracted on the bags. [Incidentally, it also shows why a sacrifice bunt by a non-pitcher is often dumb, especially early in a game, because it drops the expected number of runs. It does increase a bit the chances of scoring one, but severely cuts the chance of more]

Fangraphs have done exactly this, though for reasons I'm not quite sure about, have chosen to split the figure into a stolen-base component, wSB (calculated slightly differently) and UBR, which covers everything else. Still, you can combine those to get BsR, which is one of the factors in fWAR. So, where do the D-backs rank, collectively and individually?

The Diamondbacks collectively

I'd like to welcome back those who skipped the "math" part of this. To Cliff Note them in, there are three numbers which measure base-running ability. wSB which is runs added (or subtracted) by stealing bases, compared to average; UBR, which is the same for all other basepath actions, and BsR, which simply combines the two into one number to show how good, bad or indifferent the subject has been at base-running, again measured in runs. Here are those three stats for the entire league:

# Team UBR wSB BsR
1 Mets 15.1 0.2 15.3
2 Pirates 5.7 1.9 7.6
3 Rockies 2.8 4.2 7.0
4 Giants 6.7 0.3 7.0
5 Padres 1.3 4.5 5.8
6 Marlins 0.9 -0.5 0.4
7 Reds 4.6 -7.4 -2.8
8 Cubs -2.1 -1.9 -4.1
9 Cardinals -1.2 -3.1 -4.3
10 Brewers -7.9 3.0 -4.9
11 Nationals -4.5 -0.8 -5.4
12 Phillies -5.9 0.5 -5.5
13 Diamondbacks -0.4 -7.1 -7.6
14 Braves -3.8 -4.6 -8.4
15 Dodgers -9.5 1.0 -8.5

This does tend to confirm what we concluded in the raw numbers: it's our base-stealing which his really been the problem, with our other base-running being mediocre, rather than dreadful. I also note that, outside of the Mets, everyone else is within 15 runs of each other, so the gap between worst and best on the bags, probably only represents a couple of wins over the course of a season. Obviously, it's better to be good than bad, but that does suggest it's something, like batting order, which doesn't actually have as much importance in the final numbers, as it perhaps seems.

The Diamondbacks individually

Here are the same numbers for each member of the D-backs with 55+ PAs this season [number chosen specifically to eliminate the pitchers!]

# Name UBR wSB BsR
1 A.J. Pollock 2.2 0.2 2.4
2 Paul Goldschmidt 1.1 0.2 1.3
3 Aaron Hill 1.3 -0.3 1.0
4 Didi Gregorius 1.9 -1.0 0.9
5 Josh Wilson 0.5 0.0 0.5
6 Adam Eaton 0.8 -0.5 0.3
7 Willie Bloomquist 0.4 -0.1 0.3
8 Eric Hinske -0.2 0.0 -0.3
9 Cliff Pennington -0.6 0.2 -0.4
10 Gerardo Parra 2.0 -2.5 -0.5
11 Wil Nieves -0.8 -0.1 -1.0
12 Jason Kubel -0.5 -0.6 -1.1
13 Miguel Montero -0.9 -0.3 -1.2
14 Eric Chavez -1.8 0.0 -1.7
15 Cody Ross -2.5 -0.5 -3.0
16 Martin Prado -2.2 -1.7 -3.9

Not many surprises here either. Pollock has currently been the best base-runner we have, with Goldschmidt his usual professional self, and Hill in third. At the opposite end, Parra's competence outside of stolen-base attempts helps lift him out of the bottom tier, which is currently occupied by Martin Prado instead. For curiosity, I looked up the numbers in D-backs history (or at least, as far back as 2002, because Fangraphs doesn't have the data to calculate UBR prior to that season): our best baserunner in that time was Eric Byrnes v..2007, who rated +9.4 runs, ahead of Tony Womack in 2002 and Craig Counsell in 2005. Worst? Adam LaRoche in 2010, at -9.1 runs.


So, what have we learned over the preceding 2,000 words? Perhaps that the Diamondbacks base-running isn't quite as bad as it seems. We certainly remember the disasters, like Cliff Pennington being windmilled around third to die in Fenway, but like blown saves, the successes tend not to stick in the mind as much. On the other hand, there's certainly room for significant improvement, particularly on the stolen-base front, where a young team like ours should be an awful lot better. Smart baserunning is something that can be taught, and a good coach is likely cheaper than all but the worst free-agent hitters. Maybe we should learn from the Mets' third-base coach?