Love's deficiencies come down to effort. The question is, can he be motivated to get back in transition, make timely rotations, not fuck around too much? Absolutely. Look at someone like Zach Randolph. Lazy as fuck with the Jailblazers and now a credible defensive force. Love lacks Randolph's physical presence, but it's not like athleticism is what's holding him back. The dude is plenty strong and plenty athletic. For a Celtics example, you have Paul Pierce, who went from being an elite defender to a poor defender to a very good (but older, not quite as elite) defender. On the other hand, you have Rondo, who is trending in the opposite direction. I don't think its an accident that a lot of players put out superior defensive effort when their team starts winning. Motivation matters. Obviously you have freaks like Kevin Garnett, who has only one speed, but how many of those guys are there in the league?