That's severely underselling who and what Falcon was.
Falcon is actually one of the most highly trained member of the Avengers, period. Remember he was a member of the US Air Force's
Pararescue squad, which is a legitimate elite special forces team. This ALSO means that he had another role on the team that nobody covered: emergency first aid, since, as pararescue, he was trained in emergency field medicine.
What this ends up meaning is that he's as highly trained as Widow and Hawkeye while also having a specific subset of skills nobody else on the team has (medical training) and then on top of all that has his fancy set of wings and dual machine pistols.
There's a reason in Winter Soldier he keeps pace with Natasha without breaking a sweat and keeps his cool even while explosions and other crap is going on around him. Dude was trained to jump out of planes and helicopters while under fire to attempt rescue of injured. The real reason he couldn't keep up with Cap on his run around Washington wasn't just the super serum, it was that his monstrous brass ones slowed him down.
I'm aware, I was underselling him. That being said, he wasn't Widow or Hawkeye tier.
Black Widow was the world's best infiltrator and assassin before SHIELD recruited her and they only made her better afterword's. For all that the Avengers massively underutilized her (direct, open, combat is not her area of specialty) she was still a better combatant than most anyone else.
Hawkeye was the world's best sniper and one of its top assassins. Much like Widow, the Avengers severely underutilized him but he was, again, still a top tier combatant even outside his area of focus.
Sam was a top tier special forces soldier. Unquestionably skilled and deadly. What he wasn't was anything approaching unique or exceptional on the scale that the Avengers operated at.
In that he was like Rhodey.
Rhodey was an MIT grad and a USAF combat and test pilot who rose to the rank of Colonel and had a lot of political experience. What made him special though was his relationship with Tony Stark. He was Warmachine because Tony was willing to let him use the suit and his biggest value as an Avenger (in many ways) was his ability to (to some extent) control Tony.
Sam is Steve's Rhodey, essentially.
The difference between Falcon and Warmachine though is that one has a wingsuit and the other wears an army killer.
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Honestly, I have no real issue with Falcon and actually like him as a character. But as an Avenger? He is emblematic of everything wrong with Cap's leadership.
Falcon would be right at home on Cap's Shield strike team or the like. Cap, Widow, Hawkeye, Falcon, Bucky would make an exceptionally capable black ops team or Super SWAT team; the team inbetween the Avengers and a regular special forces team.
But for a gone to hell situation where the world is facing alien invasions? Honestly, Cap is borderline too weak to contribute to that kind of fight.
Stark, Hulk, Thor, Marvel, Vision, Strange, Wanda (assuming that she was mature, had control, and could be trusted); they are simply operating on a scale and power level that the rest lack (with the possible exception of Hope in the Wasp suit and Spiderman).