It's not meaningless at all. Another PG getting beat has nothing to do with him taking plays off. If you intentionally don't give your best effort much of the time, you have no business being mentioned as the best defensive PG. Do you think KG takes defensive plays off? Bradley takes plays off?
Rondo is a very good defensive PG, but he would be elite if he gave the effort. Considering he also does that on both sides of the ball for entire games during the regular season, you have to question his character a bit. There is a reason that he is at the top of the second tier of PG's in the league and not the best. If he gave it his all, he'd very likely be the best on both sides of the floor.