Harrell, who's 6-1 with a 2.02 ERA in nine home starts, pitched a career-high 161 2/3 innings in 2010 between the White Sox and Triple-A Charlotte. He threw 146 in the Minors for the White Sox in 2009, and then added another 10 in the IBAF Baseball World Cup.
"We're definitely going to have to watch that moving forward a little bit," Mills said.
Mills didn't rule out using a six-man rotation when rosters expanded at the beginning of September, which would have more to do with limiting innings for everyone in the rotation than just Harrell. As far as Harrell is concerned, Mills said there's a possibility they could skip him in the rotation at some point down the road.
Mills emphasized the team hasn't had in-depth discussions about limiting Harrell's workload.