"You out there warming up and you could feel how bad the turf is, and then the game kicks off and then you see guys going down back-to-back-to-back," McKinnon added. "It's very unfortunate."
The 49ers suffered several notable injuries in Sunday's win over the New York Jets, including Nick Bosa and Solomon Thomas each suffering a torn ACL that will end their seasons. Quarterback Jimmy Garoppolo (ankle) and running backs Raheem Mostert (knee) and Tevin Coleman (knee) also suffered significant injuries.
Several players were concerned about the playing surface, which is an even bigger issue since the team is scheduled to play again at MetLife on Sunday against the New York Giants.
"It's something our guys were concerned about right away," head coach Kyle Shanahan said of the turf, per Lindsay Jones of The Athletic. "Unfortunately, it's a place we have to go back to next week."
In a statement released on Monday, the NFL confirmed MetLife Stadium's turf was inspected and approved by an independent field inspector prior to Week 2's contest:
McKinnon thrived on the field with 77 rushing yards on three carries, scoring his first touchdown since 2017. He could play a significant role against next Sunday with Mostert and Coleman both dealing with injuries.