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Jon Niese's improving changeup

The lefty's changeup was a markedly better pitch in the second half of 2014. Here's what happened.

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Mets southpaw Jon Niese has something interesting going on and, if the trend continues, he might not be so average in 2015.

It's fun—and often enlightening—to compare first- and second-half splits to spot anomalies and possible mid-season skill growth of players. Niese’s 2014 splits stood out remarkably on two important metrics: First-pitch-strike rate (F-Strike) and swinging-strike rate (SwStr).

Niese has a career 61.4% F-Strike and 7.8% SwStr. During last year’s first half he struggled with a 59.2% F-Strike and 5.8% SwStr. Then something changed. In the second half his F-Strike soared to an elite-level 67.8%. His SwStr rebounded to 8.6%. What happened?

A solid changeup happened.

For most of his career, Niese had only thrown a changeup about 4% of the time. He dabbled with it when he first came up, but it was never a pitch that he seemed to completely devote himself to developing even though it was clear he needed one. His general weakness against right-handed batters was always present in his game.

In 2013 he began throwing the changeup again. Below is his usage rate against right-handed batters from that year.

After a career changeup-usage rate of 5.8% against righties, Niese threw the pitch more than 17% of the time against righties in April 2013, but he wasn’t having much success with it. A modest 8.5% swinging-strike rate was offset by a lack of command. 49.8% of these changeups were called a ball. The lack of success caused him to return usage closer to career norms.

That 8-9% usage trend against righties continued through the first four months of the 2014 season, but here’s where it gets interesting. Over that stretch, the pitch suddenly became decent!

From Opening Day to his first start in August, Niese was having remarkable success with his changeup. That 49.8% called-ball rate in 2013? Now 37.2%. His swinging-strike percentage on the pitch had spiked 3%. Jon Niese finally had a weapon against right-handed hitters!

It was at this point of the season that either Niese, pitching coach Dan Warthen, or somebody else in the Mets organization noticed that his changeup had become a very valuable pitch for him. Beginning with his August 6 start against Washington through the end of the season, Niese’s usage of his changeup increased dramatically.

Over this stretch, Niese's command of the pitch also kept improving, with a 36.0% called-ball and 12.5% swinging-strike rate. In 2014, righties hit just .239 against the changeup with a .114 ISO and a 79 wRC+.

Also interesting, the increased usage from August 6 through the end of the year may have had a side effect of increasing the whiff rate of his other pitches. Both his four-seam fastball and his cutter fooled few batters over the past few years. From April 2012 to July 2014, the four-seamer had generated a 7.3% swinging-strike rate. The cutter had a marginally better 8.9% swinging-strike rate. During the August through September stretch finish where he was heavily utilizing his new changeup?

Suddenly having to deal with a solid changeup, righties started swinging and missing at Niese’s other pitches. In this case the rising tide of his changeup definitely lifted all boats.

Why is Niese’s changeup suddenly more effective? For one thing, he did get a slight increase in vertical drop on the pitch in 2014 that he didn’t have in the past, and that certainly is driving some of the success. But he also learned how to command the pitch and throw it where he wanted, whenever he wanted. This is perhaps the more decisive factor in his success with the pitch.

If Niese can stay healthy (always a big question mark surrounding him), he’s an interesting guy to keep an eye in 2015. He doesn’t have the stuff to suddenly become an ace, but if he can neutralize right-handed hitters with this new weapon and bring those righty/lefty splits into line, he’ll be very useful pitcher for the Mets.

With the continuation of this changeup development and a little luck, a season in the area of 195 innings pitched, a 3.20 ERA, a 1.15 WHIP, and 160 strikeouts isn't out of the question. Jon Niese might not be so average anymore.