I think Allen is just suffering from a bout of "Ichigo" syndrom, he gets kicked around because the bad guy needs to appear stronger then they actually are.
The first appearance of the level 4 left us with the impression that it was stronger then several of the Noah we have met so far, but that was likely just the element of suprise.
and when I say General level, I mean 100%+
We don't know if Lenlee's innocence is at that point yet, but if it isn't, she will certainly be scary when she gets there (considering her power level right now)
Allen is already slated for being the next General(indirectly), just because of that sword, I would guess that it wasn't completely effective against Tyki BECAUSE he was a Noah, and their are still alot of Unknown elements to them.
They may not be as skilled as the General's with their innocence (as the General's are quite experienced), but their innocence is definetly within the same power range.
Generals are far from invincible either, one got taken out before level 3's were even introduced, and all 4 Generals were present when the levle 4 first appeared, the element of suprise was a huge advantage for something as strong as the level 4.
Some people are like Slinkies. They're not good for anything, but they still bring a smile to your face if you push them down the stairs.