The venerable Will Carroll confirms my initial fears:
…. It’s not news that Posey is done for the season. It is news that he might be done as catcher. While the Giants won’t acknowledge the possibility, and while Posey is insisting he’ll be back at catcher, the procedure done makes it difficult for many to think he’ll be able to do so effectively.
In essence, Posey had the worst high ankle sprain possible. “Ignore the fractured fibula,” said one orthopedic surgeon who works on high profile athletes. “It’s the syndesmosis that is going to be very, very tough on him.”
Most think that Posey will be able to come back and be able to run and hit, but the burden of crouching is where it gets a bit confusing. “Watch a catcher’s ankles during a game,” said one NL athletic trainer. “They’re always involved. They’re never north-and-south.” That burden on a repaired syndesmosis might be asking too much. Posey will still be an athlete, so it’s the specific demands of catching that will tax him, not the normal “baseball activities” he would see at any other position.
I expect the Giants will give him every opportunity to catch, but I’m not confident that it will work out.