To Drill...Or Not To Drill...

Providence day 1 is done and I'm a little bummed I shouldn't be! 21st out of 70 starters isn't bad. I'm bummed with the way it went down. I rode good, got a good start, didn't go down, didn't really make any mistakes and I pushed myself cross-eyed (lost a contact, right one this time), so why be bummed? Because I really think I could have made 18th and not 21st. Wtih a lap and a half to go I caught the guy in front of me, with a lap to go we caught the guy in front of us, with 7/8 of a lap to go another guy catches us, so we're now a group of four. I really thought I could ride away from the group and thats what I proceeded to do, try anyway! I drilled it for the last lap and everytime I looked they were all still right there. So with a quarter lap to go, one guy goes and they all follow, except me I'm cooked from trying to drop the group.
So here's the question. Did I do the right thing and continue to drill it or should I have sat up and played tired and let someone else set the pace? Maybe I could have just let off and the group would have followed my pace. I doubt it, cross never seems to be any thing other than full gas, or is it? See why I'm confused.