David Lennon David Lennon has been a staff writer for

David Lennon is an award-winning columnist and author who has been a staff writer at Newsday since 1991.

In trying to decipher what there really is to worry about with Jacob deGrom, let’s start with what could be a legitimate problem. That’s the stiff lat muscle on his throwing-arm side that cut him off at six innings Friday in the Mets’ 7-2 victory over the woeful Phillies at Citi Field.

Bottom line, it’s a bad spot, and especially for pitchers. We saw that last season with Steven Matz, whose meteoric rise was delayed two months because of a full-on lat strain. For now, with deGrom, it’s all about how he wakes up, and neither he nor the Mets will know for certain until he attempts to play catch Saturday.

The convenient postgame excuse was to blame the 47-degree temperature at first pitch. But deGrom didn’t notice it tighten up until the start of the sixth inning, when Phillies starter Jerad Eickhoff stung him for a leadoff double.

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“I yanked a few fastballs to him,” deGrom said, “and that’s when I felt it.”

Still, deGrom finished the sixth, and Terry Collins stopped him there after only 76 pitches.

Remember, deGrom twice was sidelined by injuries during spring training, first a sore thigh muscle and then, weeks later, a back issue that he blamed on a soft mattress. Both deGrom and Collins denied that Friday’s condition is related to those two problems, but with the complexity of a pitcher’s mechanics, there never seems to be irrefutable proof on that.

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“We’ll be careful with it,” Collins said. “If he can’t throw his bullpen in a couple days, we’ll have to find someone to throw in his spot.”

That’s an alarming thought, losing deGrom only a week into the season. DeGrom wasn’t ready to get upset about it, though. Not after a six-K effort with zero walks, even if it was against a thin Phillies roster that would have had its hands full with the Long Island Ducks.

“I’m hoping it’s from the elements,” deGrom said. “I’m not too worried about it. We’ll see how it feels [Saturday].”

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OK, so now that we’ve addressed the lat muscle situation, let’s get to the elephant in the dugout: deGrom’s decreased velocity. For those wondering, yes, it still was missing, just as it was during spring training. But what does that mean?

On Friday, deGrom’s fastball averaged 92.8 mph and had a 94.2 max, according to BrooksBaseball.net. And if you compare that with the totality of last season, when deGrom’s average velocity was 94.9 mph and the peak was 98.8, yes, the difference is stark.

A year ago to the day, deGrom’s fastball was at 94.9 mph in his 2015 debut, and it sizzled at a top speed of 97.3 in a six-inning, six-strikeout loss to the Nationals. So what’s wrong with him now?

Collins offered a few theories, ranging from the chilly weather to a potential hangover from last season, when deGrom totaled 216 innings, stretched from April to the end of October. But the manager remains confident that deGrom’s arm will snap into its normal shape, like an overextended rubber band. “As long as Jake feels good,” Collins said, “he’ll get his velocity back.”

In the meantime, deGrom did his job Friday. He had expert command of his five pitches, shifted speeds effectively and kept the Phillies off the board until Odubel Herrera’s two-out RBI single in the sixth. The Phillies may be headed toward a 100-loss season, but deGrom’s mission was to retire the lineup in front of him.

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“The name of the game is where the pitch is,” Travis d’Arnaud said. “It doesn’t matter how hard you throw. It’s all about location.”

D’Arnaud also explained how deGrom’s arm action on every pitch is pretty much identical, making it nearly impossible for hitters to get a jump on what’s coming. So if deGrom’s peak velocity is a few ticks slow, he can make the fastball appear to hum because of the 10-mph difference with his changeup.

That was critical to deGrom’s success Friday. But if there’s less electricity in that right arm, can he again dominate the NL’s top teams the way he has in the past?

“It will be back sometime soon,” deGrom said.

As for the lat muscle, stay tuned.