Pretty sure the form score and coach feedback have nothing to do with each other whatsoever. In the latest patch, EA tried to fix it but it's still pretty broken. I just played a super tight game (which was actually a really good, fun match) that we lost 1-0. Coach feedback was an A. I blocked a ton of shots, didn't take a penalty, had a lot of scoring chances, and I wasn't on the ice for the goal against. Form score - zero.
Frustrating since you need 100 form score in every other game to get a 90 overall if you post a zero in one game. I could understand a zero if I took the penalty that allowed them to score the winning goal or something, but I didn't. It's ridiculous to think a coach would judge one specific player when the entire team was shutout in a tight defensive match.