Pittsburgh Pirates v. Chicago Cubs: The Starting Pitchers

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Aug 27, 2015; Miami, FL, USA; Pittsburgh Pirates starting pitcher Gerrit Cole throws the ball in the seventh inning of a game against the Miami Marlins at Marlins Park. The Pirates won 2-1. Mandatory Credit: Robert Mayer-USA TODAY Sports

Arrieta’s known for a devastating sinker that baffles hitters. With four complete games under his belt in 2015, it would be easy to assume that Arrieta’s go-to pitch gets stronger as the game goes on.

Or does it? I wanted to take a look at both pitchers’ whiff percentages. This particular metric, when  coupled with seeing batters for the second and third times late in games, provides a good indicator of maintaining deception, velocity, and movement. Whiff percentage is defined as the following:

"If a pitcher throws 100 pitches at which batters swing, and the batters fail to make contact on 26 of them, the pitcher’s whiff rate is 26%."

Using that, let’s take a look at how Arrieta’s whiff percentage plays throughout games:

Note: Use caution when noting the whiff percentage of the cutter. Although that does have the highest whiff percentage, it is also by far the least used pitch in Arrieta’s arsenal.

It’s not pictured, but for the first time through the order, Arrieta loves to throw the sinker, with a raw count of 511 thrown at batters faced for the first time in a contest. As the game progresses, Arrieta does not shy away from the pitch, but it’s effectiveness takes a bit of a noticeable dip later in games, from a 9.13% whiff rate to a 6.65% rate by the time he has seen a batter for the third time. Arreita’s sinker is deployed the most out of any of his pitches – 42.87% of his total pitches to be exact.

So is this a true test of effectiveness? Yes and no. Sure, the whiff percentage drops but the .BAA (batting average against) drops as well down to .191. For the Pirates, it will be very key to identify this pitch early and lay off of it and perhaps take the chance at it dropping out of the zone.

How does Cole fare when he makes his later laps through the batting order?  Let’s find out.

Way back at the beginning of the year, I wrote that Cole’s slider was developing into a nice weapon in his saddlebag. It was very encouraging to see the slider gain effectiveness in getting batters to swing and miss as the games wore on. Cole’s bread-and-butter in previous years was his fastball, and while that remains an effective pitch, it’s clear from this chart and other stats that the slider is quickly approaching “out pitch” status.

Cole’s biggest weapon this year gains effectiveness as the game goes on, and for that, the advantage here goes to Cole.

Now, let’s drop all the stats and  just look at the intangible aspects of the pitching matchup, and draw some final thoughts.

Next: Who handles it better