....that makes no sense they are out classed by loki...in the comics 95% of all heroes are , he's a monster, but the foot soldiers/chitari they arent out of their league so they are of use. Not to mention Hawkeye is as useful as his gear, so his arrowheads can be configured/modified for a situation. Same goes for BW shes trained in a plethora of weapons, all of a sudden explosive rounds and thermal charges like hawkeye deployed are more than useful. I could see a point IF all they did was hand to hand combat but they are trained in weapons , explosives, infiltration, recon and vehicles. Its not like the alien invaders were the celestials, or the shi'ar imperial guard.
I will never get this argument the avengers takes everyone for different needs. I could see if the Destroyer showed up with one thing in mind, crush EVERYTHING ok then its a problem only Thor , Ironman, and Hulk could contend with. But a full scale incursion of soldiers that are flesh and bone???