Red flags were raised Wednesday at New York Jets training camp when oft-injured tackle Mekhi Becton missed practice due to an issue with his surgically repaired knee.

“Mekhi’s knee wasn’t up for it today, so we just held him back,” coach Robert Saleh explained.

Though Saleh put on a brave face and calmly said he hopes Becton returns to practice Thursday, there’s no doubt the Jets must be concerned. Becton didn’t finish practice Tuesday and Saleh said at the time the massive lineman was on a “pitch count.”

In other words, despite being in the best shape of his NFL career, Becton is being brought along slowly in training camp because he’s played only one game the past two seasons due to knee issues.

“We’re trying to get him back up to full speed, where he can play an entire game,” Saleh said.

Becton was New York’s first-round pick in the 2020 draft. He’s battled weight issues since being drafted and had several injuries during his rookie season. Then injuries to his right knee sidelined him for the past two seasons after he was hurt in the 2021 season opener.

There’s a big competition in camp for the five starting spots on the offensive line. Saleh has said the best five players will play regardless of position. Becton wants to start at left tackle, though veteran Duane Brown likely is on his way there. Saleh prefers Becton to play the right side, but Becton has balked at that plan.

Brown is on the PUP list after offseason shoulder surgery. The Jets expect the 37-year-old to begin practicing soon.

With Becton and Brown sidelined Wednesday, veteran Billy Turner and second-year pro Max Mitchell received plenty of reps with the No. 1 offense.