Thursday, May 15, 2014

Tigers Are Better at Baserunning This Year But Not Because Of Stolen Bases

Rajai Davis leads the Tigers in stolen bases with 13
(Photo Credit:

Even if you are only a casual observer of the Tigers, you have surely noticed that the Tigers are a different team on the bases than they were last season.  The Tigers focused, in part, on improving team speed over the off-season replacing lead-footed runners such as first baseman Prince Fielder and shortstop Jhonny Peralta with speedsters such as outfielder Rajai Davis and second baseman Ian Kinsler.  Additionally, new manager Brad Ausmus has made an effort to use the speed by letting the Tigers be more aggressive on the bases.

As a result of the new team makeup and managerial approach, the Tigers already have as many stolen bases (35) four games short of the quarter pole as they had all last year.  They also lead the American League in stolen bases after finishing dead last in 2013.  Last year, no Tiger reached double figures in stolen bases for the first time since 1973.  This year, Davis already has 13 and two others - Austin Jackson (6) and Kinsler (5) are at least half way to 10. 

There is more to baserunning than stolen bases though.  For example, a player can move from first to third on a single (or fail to do so) or advance a base on a fly ball. Baseball Prospectus uses a complex algorithm to track all kinds of base running advancement.  The BP base running statistics created by Dan Fox (now a statistician for the Pirates) include the following (all expressed in terms of runs above average):
  • GAR (Equivalent Ground Advancement Runs) - Contribution of advancement on ground outs.
  • SBR (Equivalent Stolen Base Runs) - contribution of stolen bases including runs subtracted for caught stealings and pickoffs.
  • AAR (Equivalent Air Advancement Runs) - Contribution of base runners advancing on fly outs
  • HAR (Equivalent Hit Advancement Runs) - contribution of runners taking the extra base on a hit: first to third on a single, second to home on a single, first to home on a double.
  • OAR (Equivalent Other Advancement Runs) - contribution of other base running advancements - passed balls, wild pitches and balks (evidence shows that those events are not entirely randomly and are influenced by base runners to an extent).
  • BRR (Equivalent Base Running Runs)- the sum of the five above statistics above or total base running contribution.
Note that players are penalized for making outs and also for not advancing when the average base runner would have been expected to do so.

The Tigers scored runs on the bases as follows in 2013:

GAR = -8.2 estimated runs above (below in their case) average on ground outs
SBR = -0.9 on base stealing
AAR = -4.6 on fly ball outs
HAR = -7.5 taking the extra base on hits
OAR = -0.3 on other events
BRR = -21.5 total base running runs below average

So, the Tigers were below average in all types of base running plays and were especially deficient at advancing on ground outs (last in baseball), fly balls (last) and hits (second to last).  The BRR number tells us that base running cost the Tigers an estimated 22 runs compared to the average team with the same opportunities.  This was by far the worst total in the majors.   

In 2014, the numbers are more positive so far:

GAR = -1.7
SBR = -1.5
AAR = +2.5
HAR = 0.00
OAR = +0.33
BRR = -0.3

As it turns out, the Tigers are still not doing particularly well in stealing bases (-1.5 runs) according to this relatively small sample because they get thrown out a lot in costly situations.  Where they have improved the most is in advancing on fly balls (+2.5 versus -4.6 in 2013) and hits (0.0 versus -7.5).  Overall, they are a neutral baserunning team (-0.3 runs) which is a lot better than being an abysmal base running team as they were last year.


  1. The game vs Baltimore the other day probably skews that SBR a bit.

  2. Yeah I haven't been tracking this scientifically but it does feel like there are some improvements, although that's not saying much because we have had horrid baserunning problems of a variety of types for the last decade now, so not a very high bar to surpass. But I can live with any signs of improvement!


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