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.

And to think, a little more than a week ago, Matt Harvey’s meddlesome bladder was the Mets’ biggest concern.

After Sunday’s 5-2 loss to the Phillies, however, we’ve moved on to more troublesome issues, ones that can’t be fixed by a doctor’s prescription. Such as Harvey’s rather ordinary slider and the sore lat muscle that has bounced Jacob deGrom from the rotation for an undetermined period.

For Harvey, this is likely to be an early hiccup, the 0-2 start and 4.63 ERA nothing more than a slight dip before the market correction. It happens. He was beaten by the defending world champions on Opening Night, in their house, and the Phillies ambushed him Sunday at Citi Field — with meager support from his colleagues in the ’86 throwbacks.

The deGrom situation is more unsettling. It hardly was surprising that the Mets chose to skip him for a turn; a lat injury, no matter how minor the early diagnosis, must be treated with extreme care. Steven Matz missed two months last year with a lat strain, and until deGrom heals, he’s only one tweak away from a more serious predicament.

For as talented and as deep as the Mets’ rotation is, elite pitchers are as fragile as they are rare. It took only one start to sideline deGrom indefinitely after a spring training twice interrupted by different muscle ailments involving his back and thigh.

The Mets are among the World Series favorites primarily because of a rotation stocked with four potential aces, and another, Zack Wheeler, on the way in July. But as Terry Collins was reminded in the very first week, having them all together for six months is far from a sure thing.

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“I could have told you that on Feb. 1, that nothing’s guaranteed,” Collins said. “In a perfect world, with no injuries, we have a good-looking pitching staff. But it does show you that nothing’s etched in stone.”

Such as Sunday, when Harvey against the Phillies should have been a rock-solid lock. Entering this season, he had been 8-0 with a 2.15 ERA in nine April starts. But the Phillies took a 1-0 lead in the third inning, helped by pitcher Jeremy Hellickson’s single. In the sixth, Odubel Herrera ripped a two-run homer, jumping on a slider that caught too much of the plate.

Harvey’s slider is billed as his put-away pitch. He got up 0-and-2 on Herrera, missed with a fastball, then left a slider in a bad spot. Herrera hammered it over the rightfield wall.

“It just ran into his bat,” Harvey said. “Today we needed zeroes and I wasn’t able to do that.”

Technically, this was a quality start, but Harvey would be the last person to describe it in those terms. He knows that the Mets, who have scored 14 runs in five games, are leaning on him to be better than that right now.

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Even Bartolo Colon was able to limit the Phillies to a solo homer by Ryan Howard on Saturday night, and it felt nearly as cold Sunday despite the bright sunshine, which should have worked to Harvey’s advantage. But the Mets didn’t put a runner in scoring position until after Harvey was lifted for a pinch hitter to open the sixth. By then, the damage was done.

“All of a sudden, he hit a wall,” Collins said. “But we’re not giving him much room for error, either.”

With deGrom down, the Mets will turn to Logan Verrett for Wednesday against the Marlins, and he threw what amounted to a side session Sunday in the ninth. Verrett didn’t instill much confidence with a one-out walk to the No. 8 hitter, Peter Bourjos, followed by Andres Blanco’s RBI double.

But Verrett has a few days to work on some things. Next up is Matz’s 2016 debut Monday night, and then the welcome return of Noah Syndergaard. The timing could not be better.

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