Croad announced his retirement earlier this month, succumbing to a foot injury that prevented him from playing another game after the 2008 grand final.
Schoenmakers made his debut in Croad's absence last season, featuring in 13 matches as the Hawks tried to plug gaps in their depleted defence.
Mitchell said the 19-year-old had the physical attributes to hold down a key position and had worked particularly hard over the pre-season.
"It's pretty exciting when you've got a guy who's six-foot-four or five who can run like he does and is as strong as he [is]," Mitchell said from the Hawks' training session at Pakenham on Friday.
"It's just whether or not he can adapt to the speed of our game plan and the way the AFL moves. It was a great experience for him last year but with another pre-season under his belt where he's been injury-free, I think it's a pretty exciting year for guys who are around his age."
Mitchell added that the off-season arrival of Josh Gibson from North Melbourne would break up the backline workload, but that the club had to evaluate the traditional position Croad had held before his injury.
"I think the Trent Croad role of just shutting down one big guy is probably a little bit less," he said.
"You look at the really good clubs from last year and someone like (Geelong's Matthew) Scarlett doesn't always do that role where he just really shuts someone down.
"St Kilda is the same. They were able to mix and match a little bit. I think our back half is probably going to have to be able do the same thing with lots of versatile players who can play on different opponents."
The Hawks have also been buoyed by the addition of former Port Adelaide midfielder Shaun Burgoyne, who has recovered from post-season knee surgery to start training with his new teammates.
"Everyone's pretty excited to have Shaun around," Mitchell said.
"His leadership qualities have come into the club and he has a bit of a different way of looking at things.
"He was a vice-captain at Port Adelaide so we're picking up a few things that they did and hopefully we can improve our structures around the way we do things."
In a significant slide from the previous year's flag triumph, Hawthorn finished ninth in 2009 to miss the finals.
Mitchell said the coaches and players had spent time over the summer assessing where the side could improve but that no minimum targets had been set.
"We've never really said, 'Look, we need to finish here if we want to be happy'," he said. "We have a whole bunch of KPIs (key performance indicators) we try to run through and a game style that we try and play as best we can.
"If that means we finish first, fourth or eighth, [as long as] we play well and feel like we've fulfilled our potential, I think we'll be pretty happy."
The Hawks ended a heavy training block with a lighter session on Friday. Vice-captain Luke Hodge and backman Brent Guerra were the only absentees, given the day off.
