Depends. He can be quick when the route requires an early plant. As a general rule, though, I agree.
More to the point, it's easier to get him the ball without him "winning" a route. If the corner is playing off they can hit him with quick bubbles, slants, etc. The ball will get there faster due to his proximity to the QB, giving him more time and space to catch the ball and make a move. Put him in motion if the corner is trying to play press, then have him release on the run (or from a stacked/bunched WR formation on the other side). They should have a motion package for CP anyway just to put pressure on the defense.
Against zone he can run simple drags under clear-out routes. If he comes free, great. If he sucks up the attention of the DBs/linebackers to create space for someone else, that's great too.
There are plenty of conventional ways to "manufacture" touches for CP that don't rely on him beating straight coverage with a good route.
Anyway, CP has certainly performed well thus far in his limited body of work from the slot: Targeted on 19% of his 31 slot routes (as opposed to 14% of his 164 non-slot routes), with 5 catches on 6 targets for 82 yards. It's a limited sample, but that YPRR is still 2.5x anyone else on the team from the slot and it's much better than he's performing outside. What's more, Jennings is doing much better outside than he's doing from the slot (and better than CP's outside work as well). That alone should be enough of an argument for switching them.
If it was this easy, Devin Hester would be HOF bound, for his offensive production.
Norv is very good, very trusted, very well respected OC.
We need to slow down a bit with the Norv praise. Having grown up in a heavily populated Washington fan area, I got to see (and hear) about Norv a lot.
He built his rep on the back of those Dallas super teams that won Super Bowls. He was a "great" OC because he had Aikman, Irvin, Emmit, Moose and an O Line that could move mountains. None of which he drafted. Just like Wannstedt found out (the DC on those Dallas teams) - coaching after Dallas wasn't too fun.
Let's look at his offenses after he left - Only San Diego had a consistently great one - and that wasn't due to ol' Norv. Sure, he's respected in the coaching community because he's been around the block and knows what he's doing. He also has one of the lowest winning percentages as a head coach of anyone who's coached the years he has.
When he came to San Diego I remember cheering as a Bronco fan. That Chargers team? Their offense was great (I think top 10 in the League? Maybe even top 5?). But you know what? They were that way
before he got there. In fact, I believe they were
better the year before. Let me go check that... Yep, the year before he got there they were better.
Per PFR San Diego was #1 in the entire league in points and 4th in yards in 2006, the year before Norv. They slowly descended after his arrival.
He had a good year here and there in Washington, and pounded them into the ground (on offense) the rest of the years. I know, I was there watching on local TV every week. He took over a top NFL offense in San Diego and they slowly died until in his last year they were one of the worst in The League. The year after he left,
the Chargers immediately shot back up near the top of the NFL in offense. I remember him leaving, and being so sad. The Chargers offense was explosive again. He did nothing in Cleveland as OC. Cleveland's offense has gotten better since he's left. He's doing nothing great in Minny as OC.
I hate to rant on good ol' Norv, but I had to counter your post. I grew up watching the guy because he either happened to coach a team local to me, or he was coaching in my team's division. He's a horrible head coach, and an average (at best) OC. His Dallas years have carried him. I've also read that he's a very likable guy, and he's good with his players - therefor he is able to hang around The League. When you need a stable guy to fill in before you find your real OC, you hire Norv.
No offense, Coop. You know what you're talking about and I appreciate that. This is just a rant on Norv. I'm trying to keep poor team's fans from thinking "Oh, we got Norv Turner! He's good! Right? I mean, he's been around so long, he has to be, right??"
I'll put money on Minny's offense taking an uptick if Norv leaves. Seriously, I'd put big money on it.