Tuesday, June 12, 2012

Could Bob Gibson Have Been Better In 1970 Than In 1968?

To look at this I did a regression with ERA as the dependent variable and HRs, BBs, and SOs (all per 9 IP) as the independent variables. The data includes all pitchers from 1960-1974 who qualified fore the ERA title. Here is the equation:

ERA = 2.16 + 1.42*HR + .296*BB - .134*SO

Once I found the ERA predicted by this equation for each pitcher (Pred in the table below), I divided it by the league ERA in the relevant year. That number is called Ratio. The lowest ratio belongs to Gibson in 1970 with .59. Notice that he had more strikeouts per 9 IP in 1970 than in 1968. The walks were a good bit higher but HRs were pretty close. And the league ERA was much higher in 1970 (4.05 vs. 2.98).

My crude Fielding Independent ERA for Gibson in 1968 is 2.10. But for 1970 it is only a little higher at 2.40.


Phil Birnbaum said...


For 1968, B-R says Gibson gave up an OPS of .376 with runners in scoring position, compared to .469 overall. That probably explains some of it ...

Cyril Morong said...

Thanks. I did write about his RISP performance once before. See


Also, his FIP ERA from Fangraphs in 1970 was lower relative to the league ERA than in 1970.

1968: 1.77/2.98 = .59

In 1970 Gibson had an FIP ERA of 2.29. The league ERA was 4.05. So his ratio is .565.

Not only did Gibson strike out more batters per IP in 1970 he also ranked higher in HRs allowed per 9 IP (2nd vs. 5th)