That 4/5 race is frustratingly jerky at times, I find it harder in some ways that the 3/4 or masters open (harder to sit in, not harder to get results). The 3/4 and masters are a little faster, but much smoother and don't bunch up as much. In the 4/5, people are constantly braking when they shouldn't brake and taking poor lines. Technique is huge though. Anticipating surges and efficiently holding wheels takes some practice. I'm only a couple season into racing and far from being a good crit racer, but I can average just over 200 watts if I'm riding really efficient on the same course I was getting dropped averaging 300+ watts a couple years ago.

Also, having a decent FTP never hurts, but it's not as beneficial in the crit vs. a road race. When I'm riding well in a crit, my power distribution is all at the extremes (I'm either soft pedaling or maxed). Ability to surge and recover is key. Riding off the front is the exception to that.