Rondo can have his hands full with Rose and Westbrook in a ECF/Finals matchup, but at least West is a great defender behind him.
I don't think Delonte West is that good of a defender. He is a very good help defender but he struggles against quick / explosive PGs and someone like Derrick Rose is a very problematic matchup for him.
Who doesn't struggle against those players, though? I can't really think of anybody in the league who can consistently stay in front of the quicker PG's right now. Honestly, it seems like the best defense against a very quick point guard is a very big center.
Well, it's relative to your position / peers and relative to his position Delonte West is not a great defender.
He struggles against quick explosive guards more so than the other top defensive players at his position.
Delonte West is a very good defender against PGs with average to below average quickness. Very good against big guards. And always supplies very good team defense. But he struggles against quick guards ... which is why he is not a high level defender at the position. Merely a good one (a plus defender overall).
In other words, Delonte defends some types of players at the PG spot very well and others not so well + always plays quality team defense.
For example, I'd be very happy putting him on someone like Chauncey Billups. Or the Jarrett Jack's of the world.
However against Chicago and as capable a scorer as Derrick Rose, I want Rondo's minutes tied to Rose's as much as possible + I want to keep Delonte West away from Rose whenever possible because Rose will frequently tear apart Delonte West whenever they are pitted against one another.