Gerrit Cole reached 300 strikeouts for the season Wednesday night, an impressive feat given that he only pitched 200 1/3 innings. It’s part of a long-term trend that as starters recorded fewer outs per start, their aggregate K per 9 IP increased. You can see this in the graph of the two values during the low mound era, starting in 1969.
Note that the low mound had the intended effect early in the era. The strikeout rate by starters dropped, and they actually went a little deeper in games. That started changing after 1978, but the fall in innings and the increase in K rate was slow. Then, in 2015, starter innings go into free fall. That was the season the Royals won the World Series with a four-inning bullpen. Teams not only moved to using openers, but plan entire games around the bullpen. The change looks rather jarring in chart form.
In the context of these last few seasons, Cole’s 300 K season may be the greatest 300 K season of all time.
I have wondered how much of the increase in strikeouts is due to the pitcher’s improvement and how much due to the hitters no longer caring about the strikeout/swinging for the HR. I keep waiting for someone to go Moneyball and utilize the underappreciated skills like speed, defense and contact hitting. Throw in a 4 man rotation( since no one throws over 100 pitches anymore), and some platooning. Might be fun..?