Barred Rocks are not what I'd call "aggressive". They are active, intelligent birds and need enough room. If you don't give them enough room or good conditions, same with Delawares, you will have trouble, maybe more than with a docile dustmop chicken like a Silkie. They hold their own in any flock situation, are rarely at the bottom of the pecking order, but I would never classify that as aggressive.
That said, some birds can cause issues and it's just an individual thing, not a breed thing. If Barred Plymouth Rocks were troublesome, they would not be my favorite breed--I'm a "work smart, not hard" kind of gal. Never had any BR cause any issues like you're describing and I've had them for almost 7 years.
I agree with terryg on the "give them something to do" part for sure, if someone is causing issues. I had one crossbreed hen who always, ALWAYS plucked her rooster's saddle feathers. Didn't matter how much protein she got or what rooster she was with. She just had that habit. Nitpicky woman, LOL.