Mains: Where have you gone, Tony Womack?

From SABR member Rob Mains at Baseball Prospectus on January 25, 2018:

What’s the frequency of sub par hitters who are speed merchants in baseball today compared to earlier years? 

I used a couple of familiar statistics to analyze this, plus one that not all of you may know. BP’s BRR measures Baserunning Runs. Here’s our definition:

BRR measures the number of runs contributed by a player’s advancement on the bases, above what would be expected based on the number and quality of the baserunning opportunities with which the player is presented, park-adjusted and based on a multi-year run expectancy table. BRR is calculated as the sum of various baserunning components: Ground Advancement Runs, Stolen Base Runs, Air Advancement Runs, Hit Advancement Runs and Other Advancement Runs.

Basically, BRR measures all the contributions to scoring a player provides on the basepaths, from stealing bases to taking extra bases on hits to advancing on outs.

I looked for players like the aforementioned [Omar] Moreno and [Vince] Coleman, who were outstanding baserunners but sub par hitters. I chose a BRR value of 5.0 or greater to define an outstanding baserunner. Since 1950, the first year for which we calculated BRR, there have been 925 players with a seasonal BRR of 5.0 or more, an average of nearly 14 per year. Then, of those 925 players, I selected those whose on-base percentage and slugging percentage were both below the league average that season.

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Originally published: January 25, 2018. Last Updated: January 25, 2018.