Most definitely. He has stated this already too. I think a lot of it also probably had to do, with us not really having a backup, except for RKIII. He would be fine IMO, but our system doesn't fit his style. This year, we at least have a QB where we won't have to change to fit him, which will help us and Martinez.
Accountability, I don't believe he was 100% physically, until towards the end of the season. I don't remember which game it was, but there was a run that I remember him limping going into the endzone. The last 10 yards you could see him slow down. Between that, and the mental aspect of it, I strongly believe he did not play to his full potential.
This year, I hope we see the real Martinez. I think we will too.