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It’s time for Ian Kennedy to ditch the 4-seam fastball

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Hitters are teeing off on Kennedy’s fastball, and it’s about time for a change.

MLB: Kansas City Royals at St. Louis Cardinals Jeff Curry-USA TODAY Sports

Ian Kennedy has one of the better spin rates in baseball on his 4-seam fastball. Before his start against the St. Louis Cardinals last night, Kennedy’s 4-seam fastball was spinning at a rate of 2,411 RPMs. That’s good for 5th among 34 pitchers who have thrown at least 400 4-seam fastballs in the MLB this season. In case you’re unfamiliar, here’s what a 4-seam fastball grip looks like:

The idea of a 4-seam fastball is to put as little resistance as possible on the pitch. 4-seam fastballs are typically a pitcher’s fastest pitch, and also his straightest. It’s your typical fastball. The most basic pitch in all of baseball.

Ian Kennedy used to have a very effective 4-seam fastball. His high spin rates and the unique movement he would get on the pitch made it tough for hitters to square up on a regular basis. Unfortunately for Ian Kennedy and the Royals, Kennedy’s fastball has been one big meat pitch so far in 2018.

Here are some numbers that opponents are putting up on Kennedy’s fastball, before he was hit around a bit in St. Louis - .330 BA, .602 SLG%, .416 wOBA, 82.6 mph average exit velocity, 30.4 degrees average launch angle, with 6 home runs. That’s uhh...not good. Ian Kennedy’s 4-seam fastball has been a serious liability to himself and his team this season, and it’s time for Kennedy to start ditching the pitch altogether.

I’m gonna give you some numbers for a group of pitchers, and then we’re gonna figure out which of these things is not like the others:

  • Justin Verlander - 1.05 ERA, 2.19 FIP, 2.7 fWAR, 2,615 RPMs, 94.8 mph avg
  • Max Scherzer - 1.78 ERA, 1.83 FIP, 2.8 fWAR, 2,515 RPMs, 93.7 mph avg
  • Luis Severino - 2.35 ERA, 1.98 FIP, 2.6 fWAR, 2.354 RPMs, 97.6 mph avg
  • Ian Kennedy - 4.98 ERA, 4.46 FIP, 0.5 fWAR, 2,411 RPMs, 91.8 mph avg
  • Chris Stratton - 4.92 ERA, 4.44 FIP, 0.2 fWAR, 2,444 RPMs, 91 mph avg
  • Marco Estrada - 5.15 ERA, 5.27 FIP, 0.2 fWAR, 2,323 RPMs, 89 mph avg

There are six pitchers. The first three spin the ball very fast and also throw pretty dang hard. The next three pitchers spin the ball very fast and throw very average speeds or below average. The three pitchers that throw hard all have over 2 fWAR, the three that don’t...don’t.

Look. Ian Kennedy will probably never be a good starting pitcher again, it’s about time we all face that (mostly talking to myself, I had held out hope until recently). But the Royals need him to start pitching better given that they gave him a $70M contract just a couple of off-seasons ago.

One big step in the right direction could be for Kennedy to develop a good 2-seam fastball. If you’re unaware with what that looks like, it’s not that much different than a 4-seam fastball:

Compare that to the picture of the 4-seam grip that I showed you above, and you can see that there isn’t much different about the two. The finger spacing is pretty similar, the ball simply turns in the pitcher’s hand, putting the pitcher’s fingers on different seams. Gripping the ball with two seams instead of four allows the ball to spin a little bit differently, giving it some good arm-side run as it approaches home plate. Often times this movement isn’t particularly significant, but it can be just enough for the ball to run off of the hitter’s barrel and onto the end or handle of that bat, turning a 400-foot home run into a 330-foot fly out.

Let me go a little bit further with my reasoning here.

Here is Ian Kennedy’s heat map so far in 2018:

Yikes. Look at the middle of that zone. Now look at Max Scherzer’s:

Notice the difference in the two? Where Ian Kennedy’s heat map is rising up and in to a left-handed hitter, Max Scherzer’s is creeping lower and lower. Let’s take a peak at Bartolo Colon, who has an ERA of 2.82 at the ripe old age of 44 and throws 2-seam fastballs 68.8% of the time:

A little more rise up and in to a left-handed hitter, yeah? That 2-seam fastball with arm-side run allows pitchers to back-door right-handed hitters a little more than a 4-seam fastball does. Something Kennedy used to get on his 4-seam fastball before it suddenly straightened out this season. For proof of my claims, let’s take a visit to Brooks Baseball to check in on Kennedy’s fastball movement through his career:

  • 2013 horizontal movement rating: 7.69
  • 2014 horizontal movement rating: 7.24
  • 2015 horizontal movement rating: 6.53
  • 2016 horizontal movement rating: 6.74
  • 2017 horizontal movement rating: 5.99
  • 2018 horizontal movement rating: 4.84

For what ever reason, Ian Kennedy has lost a ton of movement on his fastball throughout his career. Throwing the pitch with two seams instead of four ought to allow Kennedy to gain back some of that movement, without having to sacrifice much velocity (which he doesn’t have a ton of in the first place).

Ian Kennedy may be beyond repair in terms of what the Royals expected when they gave him $70M, but he may be able to salvage the next couple of seasons with a couple of changes. At some point, every baseball player must make adjustments to their game. Felix Hernandez is going through it right now in Seattle. James Shields went through it in Chicago. It happens to every one with age, and now it appears to be Kennedy’s turn to adjust to Father Time.