Mains: Six baserunning records that ought never to be broken

From SABR member Rob Mains at Baseball Prospectus on November 8, 2018:

I’ve written articles recently about the slowest and fastest teams ever. By slowest and fastest, I was looking for a willingness to take extra bases, not just footspeed. I did this analysis using a rich data set generously shared by Sean Forman of

As a follow up, I looked for individual records instead of team records. As I’ve noted, and you probably know, baserunning was much more, well, I suppose some would say aggressive, but I think reckless is more appropriate, years ago. One of the reasons I found so many contemporary teams “slow” is that players today—and their coaches—have an awareness of sabermetric concepts like run expectancy. Better to hold back and give up a tiny fraction of a run than risk getting thrown out at a greater cost.

In 2018, a team whose leadoff batter hits a double could expect to score 1.0801 runs in the inning. If he stretches it to a triple, the run expectancy rises to 1.3076. If he gets thrown out trying, though, the run expectancy drops to 0.2733. If taking that extra base is less than about an 80 percent proposition, the runner is better off staying on second base.

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Originally published: November 8, 2018. Last Updated: November 8, 2018.