Avery plays more of the 2 on offense but he defends the PG position.
Point guards are going to "exposed" more because they are constantly defending the point of attack. Also, I think every point guard has games/plays where they take breaks. Most guys can't run the team and commit 100% to defense and have enough left for a full 82 game season. (Nobody is more transparent on the on/off games than Rondo.)
But, yeah, Chris Paul is box score elite but when you watch games, he's seems fairly average. Defense nowadays in general is tough to judge because it is such a team effort. Jeff Green does some great work guarding his man but he's often out of position for the team D, which is why Doc often goes with Brandon Bass in crunch time.