Larry was a better team defender, and that points to the key difference.
Larry was a very good team defender. I'm not sure about better than McHale, though. McHale was very good at providing help, rotating, etc., and he could cover small forwards and centers as well as PFs.
Based solely on individual skills, abilities and contributions, you know, one might even go for Mchale.
If the NBA was a one-on-one game, maybe. However, if you look at individual skills in the 5-on-5 game (i.e., passing, court vision, instincts, etc.), I'd still take Larry. I think in terms of those individual skills, abilities, and contributions, McHale only trumps in post-scoring and defense, as mentioned. Larry was better in every other area.