I see 2 things, Definitely over watered, and I think those are plastic pot's? If so get rid of them. On your next run get some fabric pots, your roots need to breath! Plus they will prune them self's for better air flow in the pot. You will see a big change in your plants.
I'd check your PH . As far as root bound is concerned, it can be a REAL prob if it gets too bad. Many times after I've noticed a fading plant, and I transplanted it, and within a few days she was jammin again . Like KJ and MD said, plastic pots should only be use as a temporary pot. Fabric pots are the way to go !!!!