If memory serves me correctly, McKinnon was a 3 down LB. He was considered undersized back then at 6'0 242 but he was a tackling machine who could cover RB's and TE's on short routes. He also was capable of providing a little pass rush. Minter is strictly a run defender.
McKinnon was a garbage defender who played for some garbage defenses. Here are the comps that Pro-Football-Reference has for his career:
Harold McLinton, Tommy Nobis, James Francis, Keith Butler, George Jamison, Mark Arneson, Reggie Wilkes, Rob Fredrickson, Don Hansen, Fred McNeill
A real honor roll of mediocrity.
Minter and McKinnon are exactly the same size at 6'0", 246. McKinnon somehow had 5 INTs and three forced fumbles in his third season in the league, which he never came close to replicating.