The Mets' Matt Harvey throws a bullpen session during spring...

The Mets' Matt Harvey throws a bullpen session during spring training on Feb. 13, 2018. Credit: Newsday / Alejandra Villa

PORT ST. LUCIE, Fla. — Why not?

It’s an easy enough question, but one that Mets pitching coach Dave Eiland considers in serious detail. Why can’t the bottom three in this rotation be what everyone once thought they could be? And, perhaps more specifically, why can’t Matt Harvey be the pitcher he was in 2015, or 2013? If he was once, why can’t he again?

“You said the sky was the limit then,” Eiland said, referencing 2015. “The sky is still the limit. Why not? I’m a very optimistic person, but realistic at the same time, too.”

Eiland, the pitching coach who helped lead the Yankees and Royals to world championships in 2009 and 2015, displayed both qualities Wednesday in his first news conference. Harvey, he said, definitely has picked up a few bad habits and mechanical flaws since his All-Star season in 2013. That’s the realism. But who says they can’t fix them? That’s the optimism.

“Mechanically, I’ll be honest with you, it looks like he got into some bad habits, simply because he had some injuries and he was probably doing something — it looks to me like he was probably doing something with his lower half to help his upper half, which is his arm,” Eiland said of Harvey, who was never quite the same after undergoing rib removal surgery for thoracic outlet syndrome in 2016.

“He’s aware of it. We’ve talked about it. We’ve looked at film,” Eiland said. “Matt was here early. We got some sides in here in the past week and he’s gotten back on track a little bit. To get him back to the level of 2013, certainly that’s our goal. We’ll see where it takes us.”

Harvey hasn’t been made available to speak, but he did come to camp in excellent shape, and there already are changes to his delivery. Eiland said he’s healthy. The righthander said last year that after returning from surgery, he did find himself trying to compensate for his arm.

He ended the season with a stress fracture in his scapula, depleted confidence and with a history of off-the-field issues, too. Most memorably, he was a no-show at Citi Field in early May, leading the Mets to check on his welfare at his apartment (he apologized to teammates and was suspended three games). It turned out, he was out late the night before, spent the morning golfing and left himself in a “bad place” to play baseball, he told the media at the time.

His fastball was barely nicking the low 90s and had lost much of its late movement, leading to a bloated 6.70 ERA over 19 games and career worsts in home runs allowed, runs, walks and WHIP.

This year, under new manager Mickey Callaway, things are decidedly different. Routines are already in place, and Callaway spent the morning in the weight room with the pitchers driving home the fact.

“We used the word ‘accountability’ a lot,” Callaway said. “We wanted to let them know that we were going to hold them accountable [for their routine].”

Though the coaching staff is preaching discipline, it doesn’t mean Harvey’s past ills will be held against him. Eiland said he couldn’t really speak to Harvey’s confidence yet because he doesn’t know him well enough, “but I’m getting to know him and I have every reason in the world to be optimistic.

“What’s happened in the past is in the past, and that’s where we’re going to leave it. What matters is what we do today moving forward.”

And if along the way, they move backward to the right parts of Harvey’s career — say, to 2015 or 2013 — that’s perfectly fine, too.

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