"He's got a lot to learn," Mitchell noted.
"With some of his footy stuff you just think, wow. And so much of how he plays comes naturally to him.
"He will be a good player, but he has a lot to learn about professionalism, lifestyle, game-plan and defensive actions.
"His good is very, very good. His bad just needs to get a bit better before he's ready for AFL footy," he said.
Garlett was touted as a top 10 pick at the 2012 NAB AFL Draft, but was overlooked because of a series of off-field concerns.
Hawthorn coach Alastair Clarkson remained in touch with Garlett throughout 2013, during which he starred for Swan Districts in the WAFL and finished in the top 10 in the Sandover Medal.
The Hawks used their second round selection at last year's draft, No.38 overall, to bring him to the club.
Meanwhile, Mitchell has lauded the attributes of boom ruck recruit Ben McEvoy.
The 91-game St Kilda ruckman was swiftly dealt to Hawthorn at the start of the trade period as a ready made replacement for Max Bailey, who retired shortly after the Grand Final win over Fremantle.
Mitchell says it will be the first time in his 13 years at Hawthorn that he has played with a mobile, running ruckman.
"It's the first time I have played with a ruckman who I guess is considered an elite runner," he told AFL.com.au.
"I know when you play against them you have to know what to do when they get away and how you cover them, so it gives us another dimension.
"I imagine it's hard to coach against a team with a mobile ruckman.
McEvoy was touted as a future captain of St Kilda and has blended in brilliantly at Hawthorn.
"You wouldn’t believe how strong a personality he is, and he's always throwing up ideas and suggestions," Mitchell said.
"He won't be a permanent member of the leadership group, but he will have some influence and I would imagine he would become a leader at the footy club at some stage in some capacity."
@afl_hashbrowne
