Pressure busts pipes & makes diamonds...
I'm glad he's being hard on them, it's what they need.
Keep pushing until they show you exactly what they're made of, don't crown'em & make'em think that they've arrived.
Practice & scrimmages should be as hard as possible, because when game time comes your opponent isn't gonna go easy on you. Every championship team in both College & the NFL all say that their practices were harder than the actual games.
Don't let up one bit, if it takes until 15min before kickoff keep drilling it in their head that they need to be better & they must compete at all costs as if their life depended on it... No other standard will be accepted, that how you toughen them up for battle, that's how you win.