This is how Rondo has played his entire career.  He plays sloppy, often lazy basketball in just about every game that is not against an elite PG or elite team.  He just does not have the focus that he has against the Paul's and Rose's or Heat and Lakers.  
And, given the number of minutes he has been playing lately with West out, it is magnified, since he is also pacing himself in games, and not taking unnecessary risks where he could get hurt or in foul trouble.  
This is just something that needs to be accepted about Rondo's game.  It has nothing to do with Perk.