The best way to take down a big back is the Hawk Roll Tackle......eyes thru the thighs, wrap, squeeze, and roll.
They did seem to improve the their fundamentals during the game, esp. the 2nd half. I am sure they got a reminder on the sideline and in the locker room. First game where most your starters have not played a ton especially last week and taking on a very good power back I think they needed to knock off the rust a bit. No worries.