Manson' play before his injury and after his injury are two different types of players. I was quite surprised to see Manson return earlier than expected from his injury. It's possible that Manson's brain and his actions weren't on the same page, which is due to his injury. His mind might be moving the same before the injury, but his body isn't responding to mind. Manson was bad when he returned from injury. With a longer time off to fully recover as well as get back into shape (I believe Zegras denoted that Manson was one of the players he would see working out with him), it's possible we get Manson that's 100% healthy to play well again.
In baseball, pitchers who have had Tommy John Surgery, ulnar collateral ligament reconstruction, run into this problem. Sometimes, it takes a year after the pitcher is cleared to play for their actions to return to form.