McInnes is a long-term fan of the former Inverness player, and was not swayed by the forward's under-par 2012/13 season.
The winger is his own fiercest critic and was scathing of his own performance at the end of his debut season with Aberdeen.
But McInnes is confident that Hayes has the weaponry to terrorise Premiership defences, and has shown his trust in the forward by giving him a free role on the pitch.
And Hayes has already repaid his manager's faith with a tireless opening-day performance against Kilmarnock where he chipped in with a goal.
McInnes said: “Jonny’s performance was terrific. He was brave, always on the move and never stopped running.
“We are all pleased because we know how desperate Jonny is to do well.
“He is very hard on himself at times. So much was expected of him when he came from Inverness last year and it could be he was trying too hard to impress.
“But I can assure Jonny myself and Tony Docherty were delighted he was already on the books when we came to Pittodrie.”