Paul Sewald has two plus pitches, a four-seam fastball that he throws about 57% of the time and a slider he uses 43%. He's ridden those two pitches to a successful career as a reliever and over the last couple of seasons has developed into one of the best closers in the game. His arrival in Arizona last August was the catalyst for a complete turnaround for the Diamondbacks bullpen that they rode all the way to the World Series.
It was in that World Series however that a couple of flaws in his game rose up, exposing some areas of weakness. Sewald depends on deception and when hitters, especially left-hand hitters face him multiple times, they start to be able to figure him out. He also becomes predictable, as if it's not the fastball, then it's the slider. Without a third pitch, hitters can guess and often guess right.
Corey Seager had seen plenty of Sewald in his career, and when he launched a 9th inning game-tying home run against the closer in game one of the World Series, he knew what was coming and ambushed him.
To combat this Sewald is trying to develop a changeup this spring. "If you're not evolving in this league you're going to get passed up," he said. "I'm lucky I've been in this league a little while, I'm going to face guys for the 10th, 12th time. You've got to try to show them a little something different."
For his career, Sewald has a .629 OPS against right-hand batters but .729 against left. That is because he allows a home run every 32 AB vs. RHB while it's just 21 vs. LHB. Developing an above-average changeup would be the ultimate weapon against left-hand batters.
With a typical overhand delivery, the pitcher will pronate (rotate counter-clockwise) their wrist to get late arm-side movement in addition to the drop. However with the unorthodox delivery Sewald has, he's never been able to find a grip or approach that's worked in the past. He's looking to throw across, stay on top of the ball at release, and let it fall. While it's not a splitter, he's looking for similar movement.
"I want to make sure the movement profile is [it's] dropping, that's the goal," said Sewald. "I need something that falls straight into the ground against lefties to get them off the rising fastball or sweeping slider."
Sewald threw a couple of them today in his first spring training outing of the year against the Angels Nolan Schanuel, and they looked pretty good, as he induced a ground out. Sewald has a long way to go, however. He has six or seven more spring outings to dial in the pitch and get ready for the start of the season. If he feels the pitch isn't good enough, he will not use it in the regular season.
"I'm not going to throw it if it's not good enough to be a plus pitch," said Sewald. "I have two plus pitches, I don't need a third average pitch. If it's not good enough to punch out Shohei [Ohtani] and Freddie [Freeman], it's not going to make the Opening Day roster."
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