In absolute terms, we know that strikeouts are at an all-time high. We see it in box scores, talking heads consistently discuss and lament the phenomenon on broadcasts, and in truth, it’s been going on for years. We’re left to wonder and analyze where the ceiling is for this trend, and exactly where the line between passable and unacceptable strikeout totals for batters begins and ends. For pitchers — whose velocity is a main factor in the increased strikeout numbers — going to work must be that much more enjoyable. And, in 2015, it was most enjoyable in terms of strikeouts for the rotations of the Chicago Cubs and Cleveland Indians.
If we look at strikeout rates for individual team seasons over the course of baseball history, no one struck out batters at a higher clip than the rotations of the 2015 Indians (24.2%) and 2015 Cubs (23.9%). That isn’t really surprising given the strikeout trend of recent years, but in mid-June of last season, the Indians’ rotation was actually on pace for the third-highest league-adjusted strikeout rate since 1950. At that point in time, they were striking out a historic rate of batters in a historic strikeout period, which is the sort of thing that tends to lend itself to positive team results. It didn’t, but most of that wasn’t the rotation’s fault (hello, team defense!), and the ridiculous strikeout pace didn’t quite continue into the second half of the season.
In the end, they finished as the 41st-best league-adjusted strikeout rotation, which really isn’t too bad: they ended up striking out almost 27% more batters than the league average starting rotation in 2015. Here’s the 2015 Indians compared to the best 15 league-adjusted strikeout rotations since 1950 by K%+ (percentage points above average compared to a given year’s league average strikeout rate):

In case you’re wondering, the 2015 Cubs finished 105th-best, with a K%+ rate of 120. Also not bad, but it’s illustrative of just how many strikeouts a team has to amass to make a run at breaking the record. And so I wondered: what strikeout rate would it take in 2016 to break the league-adjusted rate? And do the Cubs or Indians (or another rotation) have any realistic shot at breaking it?
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