Oh the chitauri did go flying back when Thor hit them alright. Cap is a super solider, of course he'd hurt them fighting hand to hand...:
The chitauri didn't go flying. Certainly not very far. Cap is a super soldier but strength still within human limits and still had some trouble when fighting regular human strengths people in tws. So for reference, someone getting hit by the hammer would probably just look similar to the punch iron man does in im1 on the terrorist. Funny, but not a messy explosion of blood and guts.
Cap took on a Quin Jet in Cap 2, what's your point?
If you're referring to the elvator scene, there were way too many people in there and it was a small space. Of course he had trouble fighting them. I recall him owning the terrorists in that ship at the start without breaking a sweat. The only person Cap had trouble fighting was Bucky (because he received a super soldier serum as well). He kicked everyone else's ass.

t:, what in your opinion leads to AOU?