Stats are basically a wash. Sif is a little stronger and faster and cage has a slight durability edge but....
Sif mops the floor with him. Way more skilled.
THE
TheVaultDwellerFront line cannon fodder
Yeah, in this fight, I'd say XP and skill counts for a lot, and Sif is an Asgardian warrior who has likely been fighting alongside people like Thor and the Warriors Three for centuries.