When the news broke at the end of the season that Indians pitching coach Tim Belcher would be stepping down from his post, I made note of the similarity between the Tribe staff’s light-on-strikeouts approach to pitching during his tenure (Cleveland ranked last in the majors with a 6.2 K/9 over the last two years) and the pitch-to-contact disposition Belcher exhibited (he had a career 5.6 K/9 rate and whiffed fewer than five batters per nine in half of his 14 MLB seasons) during his own playing career.
Then bullpen instructor Scott Radinsky was named as Belcher’s successor. Radinsky wasn’t exactly Randy Johnson during his own playing career, but he had a career K/9 rate of 6.7—interestingly, that’s highest for an Indians pitching coach since Don McMahon was in charge of the staff in 1985—and his strikeout rate had a peak of 8.3 K/9.
Naturally, I wondered then if having a pitching coach with more personal experience as a strikeout pitcher would lead to the Indians staff missing a few more bats. Today, we have an answer.
In a post at Beyond the Box Score, I looked at every MLB team in the last 10 years whose pitching coaches had experience of their own pitching in The Show. I then compared the coaches’ career strikeout rates to those of the teams they mentored and actually found a slight negative relationship. This is because of the influence of players’ preexisting abilities and doesn’t mean that coaches preach the opposite of what they had done, but that the relationship was negative is still interesting.
To account for the bias of what the players can do, I identified the 30 occasions in the last 10 years in which a pitching coach with MLB experience replaced another coach who had pitched in The Show. (Two of them were on the Indians: Belcher replaced Carl Willis in 2010, and Willis replaced Mike Brown in 2003.) I then took the differences between the new and old coaches’ strikeout rates and between the team’s strikeout rates in its first year under the new coach and its last season under the old coach.
The results: The negative relationship persisted, although it was small enough as to be essentially insignificant (R=-.11, R2=.01). In general, that means there is no evidence to suggest that coaches mold their pupils to be strikeout or contact pitchers just because that’s how they had pitched themselves.
That doesn’t mean pitching coaches are irrelevant—such a suggestion would be ridiculous—nor does it mean that Radinsky won’t try to get his staff to miss a few more bats. But we shouldn’t expect Justin Masterson‘s strikeout rate to go up in 2012 just because his pitching coach’s did.