I suck in the wind. My friends that are bigger than me do not struggle nearly as much as I. So I tuck in behind and refuse to pull.
I have had my arse handed to me over and over in crits by big guys. It took 7 years before I could out sprint one of my buddies and that was due to him having cancer.
Big guys have their strengths.
It sure is fun to try and sprint with them.