I haven't tried it yet regarding running plays. Playing as the Cowboys, my O-line does a great job of picking up their assignments, and I am playing on all pro with user sliders defeated.
I will say that since the latest patch, max protection is working
somewhat better. However, it has been my experience that if you call for max pro in a shotgun formation with the tight end inline, it is advisable to also slide the protection to the tight end side. That way, your tight end won't be assigned to block an edge rusher by himself and blockers engaged in double-teams will do a better job of getting off those blocks and picking up blitzers as necessary.