Ryan Nassib may not have as high of a ceiling as EJ Manuel when all is said and done, but Nassib knew the Offense and was productive running it. Ryan Nassib is also built like a tank.
So considering the injuries we had to work through, along with all 3 QB's completely new to the Offense its very possible Nassib would have given Buffalo a better win /loss record IMO.
After seeing some of the big name QB's like Cam Newton and Andrew Luck or RGIII come into the league and have success early on from a production standpoint, the bar has been set very high.
Myself personally, lets see what players are doing 3 or more years down the line from being drafted, when a more accurate evaluation can be made.