Kirk Rueter and Pitchers Whiffing Pitchers

Roy Halladay didn’t have his best stuff against the Padres on Saturday, even walking three consecutive batters for the first time in his career. He still managed to allow just two runs over seven innings and recorded five strikeouts in the process, which is a pretty good result for lacking his best stuff.

His strikeout total was respectable, but I couldn’t help but think that it was inflated. Two of those strikeouts came against Cory Luebke, his pitching counterpart. Outs against opposing pitchers have to be recorded somehow, but his overall line would have been less impressive with those punchouts removed. It doesn’t matter in the context of that specific game, but in evaluating true talent strikeout ability, it makes some sense to remove opposing pitchers from the equation.

It’s known and established that the major difference between both leagues is the designated hitter. Pitchers switching from the American League to the National League typically see their strikeout and walk rates improve. They get to replace David Ortiz with, well, Cory Luebke. The inverse is also true of National League pitchers making the switch to the American League.

Isn’t it possible that certain pitchers who notoriously struggled upon switching from the NL to AL did so because their strikeout rates were heavily reliant on taking advantage of fellow pitchers? This isn’t to say that striking out opposing pitchers is meaningless, but rather that it falls into a different evaluative bucket as something we may need to normalize in order to get a more accurate gauge of a true talent level.

Along those lines, a few questions came to mind while watching that Phillies-Padres game. First, and foremost, which seasonal strikeout percentage has been “inflated” the most by pitcher strikeouts? Which pitchers, and in what seasons, had the highest strikeout percentages against their colleagues? And whose strikeout totals consisted of the highest percentages of pitcher whiffs?

To start, pitchers with at least 200 batters faced and 30 pitchers faced in a season were pooled. Next, strikeout rates specifically against opposing pitchers was calculated. Finally, that strikeout rate was compared to strikeout rate against batters only, with the computed difference defining the effect of pitcher whiffs on the overall rate.

Here are the five biggest SO/PA changes when pitcher strikeouts are removed:

Because pitchers only tend to face opposing pitchers between 30-60 times in a season, the magnitude of the effect is reduced. However, as the table above shows, striking out pitchers at very high rates can certainly influence the overall strikeout rate. Tom Walker’s strikeout rate looked pretty good in 1974, and actually ranked in the Top 20 among all pitchers with 90+ innings thrown that season. However, he struck out 21 of the 35 pitchers he faced, a 60 percent clip, and suffice to say his strikeout rate wasn’t so impressive against actual big league batters.

The average strikeout rate delta among all the pitchers pooled was .012, indicating there is a non-zero effect, but that pitcher strikeouts don’t tend to have that strong of an influence over the overall strikeout rate. But in this case, we’re interested in the extremes.

Getting back to Tom Walker, his 60 percent strikeout rate against opposing pitchers isn’t even among the best of all time. Here are the top five strikeout rates against pitchers:

In the cases of Lamabe and Fryman, pitcher whiffs turned their rates from below average to above average. However, in the cases of Koufax, Prior and Carlton, all high strikeout guys to begin with, the effect was obviously reduced. Prior struck out 147 batters in 2002, 23 of which were pitchers. His gaudy 30.2 percent overall rate was still an extremely impressive 27.5 percent without pitcher whiffs factored in. His pitcher whiffs only accounted for 16 percent of his overall total. Framed that way, which pitchers in what seasons had pitcher whiffs account for the greatest percentages of their overall strikeout rates?

In the case of Candini, that answers another question in that yes, someone actually has struck out more pitchers than opposing batters in a season. It’s obviously very rare, and requires the pitcher to have very little strikeout skills, but it has happened.

Lastly, I was curious about how pitcher whiffs affected pitchers over more recent years. Sticking with the Wild Card era, here are the five player-seasons with the highest rate of pitcher whiffs to total whiffs:

Kirk Rueter sticks out like a sore thumb here, and he shows up several more times throughout the “leaderboard” as someone who didn’t record a great deal of strikeouts, but whose overall tally was greatly influenced by opposing pitchers. In his case, it would have made sense if he greatly struggled in a hypothetical league switch because not only was his strikeout rate low, but a good number of his actual strikeouts came against opposing pitchers he wouldn’t face in the American League.

There is still area to left explore here, and in the next installment of Pitcher Whiffing Pitchers we’ll take a look at some notoriously good and bad league switches and see if above average pitcher whiff rates are identifiable as the main culprits.