Agree with that, though MacKenzie seems to be making noises about those injury issues being behind him and that he's now fallen in love with the game again.
That tallies with rumours that were going round that his issues weren't entirely physical*, and that, for a while, he might not kick a ball again for anyone. Mind he played with an undetected concussion in that game when you horsed us 4-1 at Cappielow... that was the August and he didn't play again until December. He can't remember any part of the Cappielow game.
He eventually played 18 games that season, then got bombed out by Stubbs in the close season, which coincided with achilles surgery. I think that knocked him back significantly and he then didn't feature again until the relegation run-in. He was truly immense against Dundee United.
So while it appears he has a horrendous record, I think he's the sort of player for whom mental wellbeing plays a huge role and, hopefully, he's in a good place now.
* I'm not making light of that there, just for the record; I've personally suffered from depression and anxiety, and it's fucking horrendous.