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Statcast pinpoints rest as best for Harvey

NEW YORK -- When Matt Harvey climbs atop the Citi Field mound for tonight's 7 ET showdown against the Red Sox, he will be operating on 11 days' rest -- 11 days of playing catch, throwing bullpen sessions, weightlifting, watching television and otherwise acting like his usual self: a caged animal. Not since his Grapefruit League debut has he gone longer between outings, thanks to a skipped start on what would have been his turn last Sunday in Denver.

The rest may prove important -- Statcast™ tells us so. While Harvey's results have been pristine over the past month-plus, including a 1.27 ERA since the All-Star break of his first year back from Tommy John surgery, his velocity has taken a slight dip. That flies in direct contrast to fellow young pitchers Jacob deGrom and Noah Syndergaard, who -- like most of baseball's top 20 starters, as ranked by Wins Above Replacement -- have enjoyed a gradual midsummer velocity increase.

Harvey's average four-seam velocity peaked back in June at 96.44 mph, but is down to 95.9 in August. Syndergaard jumped from 96.83 in May, the month of his debut, to 97.44 in August, while deGrom's average four-seamer has risen a little each month and sits at 95.57 this month.

Tweet from @AnthonyDiComo: Looking forward to Harvey's start on Friday, Mets officials admit he's been fatiguing. Check out this velocity chart. pic.twitter.com/PvmJoBT7bY

The spin rate on Harvey's average four-seam fastball has taken a similar dip, again in contrast to his peers, peaking at 2397.74 rpms in June, and trending downward the last two months, to 2335.93 rpms. (deGrom, as with his velocity, has seen his average four-seam spin rate rise each month, and sits at 2297.5 rpms in August.)

Tweet from @AnthonyDiComo: Also this one on spin rate, a good way to measure "stuff." Looking back, Harvey and Mets say the rest was well-timed. pic.twitter.com/c99FjHrqkF

Former Major League pitcher Zach Day, who works at TrackMan, a pitch-tracking system employed by both the Mets and Statcast™, noted that spin rate correlates quite closely with swing-and-miss rate. That, in turn, is an excellent indicator of success -- one way to quantify what pitchers refer to as "stuff," or as Day puts it, "your life on your fastball." So it is worth noting that as Harvey's velocity and spin rate have fallen, particularly in comparison to the game's other elite starters, his strikeouts have fallen in kind -- from 8.81 before the All-Star break to 6.75 after it.

"I think I got tired a little bit earlier than I kind of expected," Harvey added. "I think going down the stretch, going into September and hopefully October, this little rest will mean a lot."

Video: Harvey discusses skipping start against Rockies

But Harvey has still been consistently successful since mid-June, lending credence to pitching coach Dan Warthen's contention that it's not all weariness; the right-hander's much-publicized change in approach is also playing a role. Following an Aug. 11 win over the Rockies, Harvey noted that he has been trying to pitch to contact more, at least until he reaches two strikes on a batter. Warthen has encouraged Harvey to conserve energy by operating around 90 percent until he needs a boost, meaning the pitcher's dips in velocity and spin rate are not entirely physical -- they're strategic, as well.

In Harvey's last outing against the Pirates, he opened five of his six innings with fastballs, never hotter than 94 mph. Only after he fell into trouble did he truly crank things up; after Starling Marte tripled with two outs in the third, for example, Harvey came back with three consecutive 96-mph fastballs against Neil Walker. He didn't throw a single 98-mph pitch in the game until Gregory Polanco also reached third base in the fifth, at which point he ripped off four of them in a row.

Video: PIT@NYM: Harvey gets Marte looking to end the inning

"The idea is to get him to play a little more at the 94, 95 [mph] range, try to get earlier outs, deeper in the game with less pitches, and then save that strikeout for when he needs it," Warthen said. "Most of the time when it's 0-2 and I see a 98, I know Matt's ready."

That's good news for a Mets team that will rely heavily on Harvey down the stretch, as is this: Statcast™ shows no such trends for deGrom and Syndergaard, who are not coming off surgery but nonetheless face career-high innings totals. deGrom has pitched 157 innings so far, edging toward his previous high of 178 2/3. Harvey is at 154, with a career high of 178 1/3. Syndergaard has thrown 145 1/3 innings, 12 more than his previous high-water mark. The Mets have imposed soft regular-season limits of around 205, 190 and 175 for those three, respectively.

On their next road trip, the Mets plan to skip Syndergaard in an effort to conserve innings, but he and deGrom both appear as strong as ever.

"I feel fine," as deGrom put it, brushing aside even an illness that afflicted him during his last start.

"The training staff and the strength and conditioning has a great program with us, always keeping us healthy," Syndergaard added. "My body's feeling great right now."

If Harvey can say the same in October, the Mets will have accomplished their goal.

"He's excited to pitch again," Warthen said. "He was feeling a little fatigued. He's never going to say it, but when we finally told him we were skipping him, he said, 'My arm was getting a little heavy.' Now he's starting to champ at the bit."

Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDiComo and Facebook, and listen to his podcast.
Read More: New York Mets, Matt Harvey