Has anyone ever tried to estimate peter sagans ftp and 5 sprint power, if so what would they look like?
I found a discussion of Peter Sagan's SRM data from an early stage in the 2012 Tour De France.

Also an article which discusses normal power output for various effort durations.

What matters for sprinting isn't their FTP, rather it's their power output over 5 seconds, 1 minute, 2 minutes... For the last 5 seconds a top sprinter will be pushing 22-25 W/kg, whereas 6.0 - 6.5W/kg is realistic for HC climbs.

In addition to his weight advantage, Cavendish is also one of the most aerodynamic road sprinters. This article suggests a 10% decrease in CdA can result in a 3 metre advantage in a 14 second sprint. That's a humiliating margin.