I've noticed this as well. I think they struggle with movies made by competent filmmakers just because there's less stuff to make fun of, so they have to focus and exaggerate the smaller, fewer bad parts. I think the shorts are were they're best, but I haven't looked through their catalogue recently.been watching more rifftrax lately over on cytube
seems a pretty reliable thing that the more they're working with some random weird older movie the better they end up
364 Pages is really good. I'm currently listening to their take on The Mister by E.L James. It's her "bad" novel, apparently.