Mains: The fastest teams ever

From SABR member Rob Mains at Baseball Prospectus on October 18, 2018:

Last month, I introduced a “Speed Index” to determine how much teams used their speed on the basepaths. This is not the same thing as being fast, mind you. I looked at how often teams attempted stolen bases, hit triples, and had runners take an extra base on hits as a proxy for a willingness to use speed as an offensive weapon.

Someone can be fast without using their speed as a weapon. Among 287 players with at least 100 “competitive runs” (i.e., sprints), Ronald Acuña ranks seventh in Statcast’s Sprint Speed, at 29.6 feet per second. José Ramírez is 144th, at 27.5 feet per second. Yet Ramírez attempted 40 steals to Acuña’s 21. They each hit four triples. Ramírez took an extra base on hits (first-to-third on singles, first-to-home on doubles, second-to-home on singles) more frequently, 55 percent to 54 percent. Was Acuña slower? Demonstrably (using Sprint Speed) not. Did he use his speed less than Ramírez? Demonstrably (using the measures I identified) so.

Applied to teams, I found that the 10 teams in the Expansion Era (1961 to present) with the lowest Speed Index were the 2017 Blue Jays, 2016 Orioles, 2005 Red Sox, 2017 Orioles, 2014 Orioles, 2016 Mets, 2006 Red Sox, 2013 Tigers, 2017 A’s, and 2018 Blue Jays. You may have detected a pattern. The least aggressive teams on the basepaths are all of a recent vintage.

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Originally published: October 18, 2018. Last Updated: October 18, 2018.