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Reliever JD Hammer unveils new high-powered fastball

A familiar, bespectacled face for the Philadelphia Phillies unveiled a newly found fastball in spring training this past weekend.

JD Hammer unleashed a fastball that reached over 97 mph Sunday. (Cheryl Pursell)

JD Hammer, a reliever who became popular with Phillies fans for his Ricky Vaughn-esque eyeglasses during the 2019 season, was a bright spot in the team’s 4-0 Grapefruit League loss to the Yankees in Tampa on Sunday afternoon. The right-hander recorded the last two outs of the third inning, striking out Giancarlo Stanton and forcing Luke Voit to fly out to center field with just six pitches.

“I thought JD looked really good today.” Phillies manager Joe Girardi said following the game.

Hammer, currently a non-roster invitee, threw three fastballs in his spring debut, all of which showed a significant increase in velocity compared to his last season in the major leagues. Each was clocked at 97 mph, over two miles per hour faster than his 2019 average of 94.4 mph.

This development in the 26-year-old’s game comes after somewhat of a lost season in 2020. After breaking into the majors during the 2019 season and posting a 3.79 ERA in 20 outings, Hammer was designated for assignment last February. No longer part of the 40-man roster, he was not invited to the Phillies’ summer training camp following the COVID-19 shutdown and ahead of the shortened season. He was only added to the team’s alternate training site in Lehigh Valley in mid-August, leaving him without organized baseball for much of the year as the minor-league season was canceled.

Hammer was instructed to take a break following the completion of activities at the alternate site, but began to ramp things back up in the middle of October, according to Phillies assistant minor-league pitching coordinator Travis Hergert.

The team set up a plan to get Hammer into throwing again, which included using methods that the pitcher preferred to utilize.

“JD loves long toss,” Hergert said, “so we programmed specific long toss days along with recovery days.”

Hammer later began using differently weighted PlyoCare baseballs on Mondays and Fridays to test and help build velocity. The weighted balls, a tool Hammer was already familiar with, can assist in strengthening the arm and encourage efficient mechanics.

“The focus was to move fast and powerful. The radar gun was his coach,” Hergert said.

The next step was for Hammer to begin throwing bullpen sessions every Friday. Player development staff broke down the velocity, spin direction (in oversimplified terms, the optimal axis for a pitch to be spinning on) and spin efficiency (in oversimplified terms, the percentage of a pitch’s spin that leads to movement) numbers at which Hammer’s pitches worked most effectively. He stayed in communication with Hergert to work toward replicating them in his bullpen sessions.

In studying these factors, Hammer was able to learn some of the key properties of his best pitches. The key to his fastball?

“Holding the spin direction … to get true ride/life,” Hergert said.

That, combined with improved velocity, led to Hammer showing off a fastball that looked better than it did when he was considered a potential power-arm prospect.

But Hammer worked on more than just the four-seamer.

The slider was another focus of the righty’s offseason training. Hammer worked on the pitch’s “velo and shape to get some glove-side movement,” according to Hergert. Its improvement was also notable in Hammer’s first spring training game of the year.

“I thought his breaking ball, the breaking ball he had for a [swinging strike], … I thought was probably the best breaking ball that I’ve seen him throw,” Girardi said of his 1-0 pitch to Stanton.

Of course, it’s very early – a single outing in spring training is anything but a predictive sample size – but Hammer’s stuff appeared to have reached another level in that first appearance. That doesn’t mean the right-hander ever ends up cracking an improved Phillies bullpen this season. Nonetheless, a reliever once thought to be the odd man out may have forced his way back into the conversation.

“We gave him the numbers and video feedback on ‘good’ versus ‘not so good’ pitches and backed it up with performance stats,” Hergert said. “He took it and ran with it.”


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