Take control of LB's is pretty much all I do on defense. Just do a lot of mini camp Game Situations for practice (unlock them by completing the drills with bronze or better). You'll eventually get the hang of recognizing the run, too.
You could try taking control of your linemen as my friend loves to do, though I usually avoid it (not that great at it yet). He played the drills for those guys a lot so he's gotten accustomed to being able to push through the O-line quickly to go for the sack/tackle.
Quick question: When one of those WRs gets that long catch, did you switch to switch players almost immediately? Because I swear it momentary slows down your LB the second you switch to him, even if you hold sprint while doing it.
If they catch the ball in front of your guy, they should slow down just a tiny bit for the catch, in that split second the AI should be able to catch up and make a tackle. I tend to just let the AI handle it if I'm not already there, as I seem to only make it worse =/
Which team do you normally play as, anyway?