User blog comment:JoshofBlades/Why the Empire Should Prevail Over the Stormcloaks! (part 2)/@comment-80.216.238.11-20111207040748/@comment-72.18.40.121-20120108021014

Firstly, the Empire did fall and a new emperor was crowned (ironically you kill him at the end of the DB questline)

Secondly, The average soldier, imperial or other-wise, is no Ysgrammor. They are regular folk who learned to fight.

Lastly, the Thalmor are immensely powerful. They held back the daedra when other provinces were falling apart, and they managed to defeat the empire on multiple occasions. The Stormcloaks, with their limited number and disorganized tactics, would crumble beneath the Thalmor.