MILWAUKEE -- Of all the Mets’ early-season rotation concerns -- Justin Verlander’s injury, José Quintana’s long-term absence, imperfections from others -- the most pressing may be Carlos Carrasco’s velocity drop. Over four-plus innings in his season debut on Monday, Carrasco’s four-seam fastball averaged 91.1 mph. It was the slowest average fastball of any outing in Carrasco’s 14-year career, and it played a notable role in a 10-0 loss to the Brewers at American Family Field. 

Within a different context, such data might be easier to set aside. But Carrasco’s velocity drop occurred after he skipped his final Grapefruit League appearance with what manager Buck Showalter termed right “elbow maintenance,” and after Carrasco appeared to tire toward the end of last season, producing a 7.36 ERA over his final three starts. If this isn’t time to panic, it’s at least cause for concern for Carrasco, a 36-year-old who has struggled to stay on the field over the past half-decade.

“I pay attention to my velocity,” Carrasco said, confirming that his elbow is healthy. “I want to know where I am. This is the first game. We have more games to come, and I’ll just get them from there.”

Last year, Carrasco came reasonably close to a full, healthy season, even though club oversight limited him to 152 innings. Still, it was what Showalter called an “under-the-radar” type season for Carrasco, who tied for the team lead with 15 wins.

In most of those starts, Carrasco sat 93-94 mph with his fastball. His average velocity on the pitch never dipped below 92 in a single game.

Carrasco hit that nadir for the first time in his career on Monday, appearing sharp early -- he retired six of his first seven batters, hitting 93 mph on the radar gun -- but less so in the middle innings. The right-hander allowed a walk and an RBI single to perennial Mets villain Jesse Winker in the third inning, then a two-run homer to Brian Anderson in the fourth. That came on an 88.7 mph fastball that American Family Field scoreboard data erroneously labeled a changeup.

Despite the issues, Showalter allowed Carrasco to return to the mound in the fifth inning at 85 pitches. It was a mistake. Unable to crack 90 mph against the leadoff man, Carrasco walked both Christian Yelich and Winker in succession, which forced him to watch from the bench as reliever Tommy Hunter allowed both inherited runners to score. Hunter later permitted five runs of his own, including a Brice Turang grand slam to put the game out of reach.

“Listen, we are human beings. We’re going to get tired,” Carrasco said. “Not every time we’re going to throw 93-plus.”

Earlier in his career, however, Carrasco did exactly that. According to Statcast data, Carrasco threw eight four-seam fastballs on Monday that did not crack 90 mph. He threw seven such pitches over the previous five seasons combined.

“A couple long innings … but other than that, everything feels nice, everything feels normal,” Carrasco said. “I just had some long innings, and pretty much that’s what happened.”

“He’s where he needs to be, range-wise,” Showalter added of Carrasco’s velocity.

Afterward, the conversation turned to Carrasco’s ability to rebound from this outing. Given the absences of both Verlander and Quintana (the former could return at some point in April, the latter is out until at least July), the Mets can ill afford another pitching issue. Already, the Mets are relying on sixth and seventh starters David Peterson and Tylor Megill in their regular rotation. Beyond those two on the depth chart are Dylan Bundy and Joey Lucchesi -- two veterans with ample Major League experience but spotty recent health and performance records.

Showalter dismissed Carrasco’s velocity drop for several reasons, including what he referred to as inaccurate radar guns. (Statcast technology does not rely on traditional radar gun readings.) He called the low velocity “normal” for Carrasco, even though the right-hander’s historical data contradicts that statement. The only explanation that resonated with Carrasco was his adjustment to Major League Baseball’s new pitch timer, which forces pitchers to work at a faster cadence than many have in the past.

Corroborating that, Carrasco received a timer violation before throwing his first pitch of the season, then another following Anderson’s homer in the fourth. Whether that was the driving factor behind his velocity drop remains to be seen, but on a no-good, very-bad day for the Mets, team officials were left hoping this is something Carrasco can correct.