Thanks to everyone who had questions and observations about last week’s column on career baserunning. Today I wanted to quickly address four reader queries related to the article.
First, I had noted in the column that nine of the top twenty runners in career EqBRRate (a rate statistic that includes all metrics except EqSBR) were active in 2007 indicating that perhaps either this is simply random or that it may reflect a widening of the gap between the best and worst runners of recent years. Attentive reader Justin, however, noted that the likely reason is that those career leaders such as Chone Figgins and Juan Pierre haven’t yet gone through their decline phase. Indeed, aside from Ray Durham and Tony Graffanino all those active runners have played in eight or fewer seasons. I admit that hadn’t occurred to me and when considering the graph titled “Equivalent Baserunning Rate by Age” also included in the article, it seems self-evident that this must indeed be the case. To verify this I re-ran the leaders having 350 or more Scaled Opportunities through their age 29 season (the age of Chone Figgins in 2007) and only five of the nine active players remained in the top twenty with the likes of Lonnie Smith, Eric Davis, and even Nellie Fox taking their places thereby confirming Justin’s idea.
However, while the lack of decline for active runners is certainly the biggest reason for their over representation among the leaders, taking a closer look I find evidence that the gap is widening somewhat. This is illustrated by the following graph which shows the coefficient of variation (CV) for EqBRRate over time for runners with 75 or more scaled opportunities.
You’ll notice that the CV increases over time indicating that the distance between the lowest rated runners and the highest has in fact grown larger over time. In large part this has to do with the fact that overall, runners do not advance on hits as frequently now as in the past as a simple plot of average bases gained when a runner is on first when a batter singles shows.
The reason for this probably includes a reduction of hit and run plays and increasing offensive levels in recent years, but in any case, this depressed environment provides a bit more conceptual space for elite runners to excel.
Another reader wonders whether EqOAR should be given more weight either in EqBRR or in the rate statistic EqBRRate since this identifies runners who were better at disrupting pitchers and thus disproportionately affecting the game. To that idea I would first argue that EqOAR is among the metrics that shows the least year to year correlation and so it may be the most subject to the vagaries of chance. As a result giving it more weight may push us farther from measuring baserunning skill. Secondly, the authors of The Book: Playing the Percentages in Baseball have shown that a so-called “disruptive” runner has “an enormously negative influence on the batter, enough to almost completely offset the disruption caused to the defense”. And so it would seem that giving EqOAR extra weight would not be wise.
For our third question, several readers wondered whether or not EqSBR could be included in the EqBRRate statistic. In the article I noted that this was not done since EqSBR is made up of primarily elective opportunities and so including it would dilute the idea of “pure” baserunning. While I still think that is a valid concern, it could be incorporated (as suggested by reader Dan) by treating it much the same way as the opportunities for EqOAR. That is, compute EqSBR opportunities using times on base (and perhaps accounting for context like pitcher handedness and other runners) and then compare that to the league average to calculate a rate statistic. This could then be incorporated into EqBRRate.
Finally, a reader named David asks if I could post the running numbers for the (hopefully complete) career of Barry Bonds. Although the younger Bonds never had a season like his father in 1972 when Bobby led the league with a +13.6 EqBRR nor for that matter like 1979 when the elder Bonds sunk to -7.2, Barry was generally an above average runner through the 2000 season and unlike many players with as many stolen base opportunities, recorded a positive career EqSBR total.
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