Pittsburgh Pirates rookie hurler Gerrit Cole will start Game 2 of the NLDS against the St. Louis Cardinals.
Cole has gotten better as the season has progressed. His second half ERA is just 2.85, compared to 3.89 in the first half, and his strikeout rate has leaped from 14.5% to 25.3%.
He had a 1.69 ERA in September, with a whopping 32.1% strikeout rate. Hitters managed just a .209/.276/.248 line against Cole in September.
A big reason for Cole’s success has been increased usage of his slider and cutter. In the first half, Cole threw his slider on just 18% of his pitches. He threw his fastball on almost 80% of his pitches. The Pirates broke Cole in slowly, making him focus on fastball command and getting groundballs.
In the second half, Cole has utilized his slider much more frequently, throwing it on 32% of his pitches. Hitters have managed a pitcher-like .158/.171/.233 line against Cole’s slider.
Over half of his strikeouts and only two of his walks have come via the slider. The slider has been effective against both lefties and righties, and Cole has a very small platoon split.
Even though Cole’s slider ends up in the strike zone less frequently than any of his other pitches, hitters swing at it more often than his fastball. Not surprisingly, this generates a very high whiff rate.
When hitters do manage to make contact off of Cole’s slider, they tend to hit groundballs. Cole’s slider has the highest groundball rate of any pitch within his arsenal.
Of course, pitches exist within a repertoire, and having a fastball that reaches 100 mph certainly makes a slider more effective. Nevertheless, fellow flamethrower Stephen Strasburg‘s breaking ball can’t match the effectiveness of Cole’s slider.
The Pirates have gradually allowed Cole to expand his repertoire, and hitters are suffering the consequences. While they roughed up A.J. Burnett in Game 1, the Cardinals will have their hands full with Cole in Game 2.