McGrath actually has an excellent lock-down record and provides great rebound so the balance is there. You’re right in saying that he isn’t naturally a hard nut but he isn’t a shirker either. His kicking has been fairly criticised but that is mostly when playing midfield, when kicking high around corners to no-one. Playing directly out of defence his kicking has been fine just doesn’t have the penetration.I suppose that's depends on what you're after.
IMO Hardwick is a better lock down defender, is tougher and is a better kick. McGrath can provide more run and is good in possession chains.