Oblique strain. Max is out 6-8 weeks
From The Athletic:
New York Mets starter Max Scherzer will miss six to eight weeks after an MRI showed Thursday he has a moderate to high grade internal oblique strain. Scherzer left Wednesday's game against the St. Louis Cardinals during the middle of Albert Pujols' at-bat in the sixth inning due to left side discomfort.
“I don’t think this is a major strain,” Scherzer said after the game. “But I’ve never had a left side injury before. So when I felt it, I just knew there was no way you could throw another pitch. So, just get out of there.”
After throwing an 85 mph slider in the dirt, Scherzer signaled to the dugout, making a slashing motion in front of his throat, seeming to indicate that his night was over. Manager Buck Showalter and trainer Joe Golia immediately came out to check on Scherzer. Scherzer threw 87 pitches before his departure.
From a different article in The Athletic, one titled "The Mets’ nightmare scenario? It surfaced when Max Scherzer pulled himself out against the Cardinals"
The Mets’ possible nightmare scenario comes with Jacob deGrom still on the 60-day injured list and seeking to return from a stress reaction in his scapula that surfaced in the spring and with right-hander Tylor Megill on the injured list with a bout of biceps tendinitis. The Mets, 25-14, have weathered the storm in remarkable fashion, racing to the best record in the National League East, and they continued their streak of resilience Wednesday night, battering the Cardinals before and after Scherzer’s exit.