system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Besides plot and a “weaker” suit, how did Iron Man lose to Captain America and Winter Soldier after previously going toe to toe with the likes of Thor, Killian, and Ultron? How did Cap and Bucky’s faces not get broken throughout the fight against Iron Man?
gpt
Barnes received a version of the Super Soldier Serum. Cap did as well. Neither one was a standard human and it would take a whole lot to "bust their faces".

And while their stamina and resilience was a pretty important factor in the fight, the main thing was that Tony was *not* fighting rationally. He was full on-tilt.  He was not using the suit's abilities to their fullest extent and he wasn't thinking strategically.

(I mean, flying outside and bringing the whole thing down would have been more effective than engaging two super soldiers in hand-to-hand combat.)

Damage to the Mark 46 limited his effectiveness as the fight wore on, but it had a secondary effect as well. It forced Tony to realize that in a straight-up brawl the Mark 46 was not strong enough to defeat Bucky and Steve, especially because they worked so well together (like the passing around the shield thing).

So he asked Friday to do a bit of thinking for him, and that enabled him to turn the tables to some degree.

If Stark had walked in and began to methodically destroy his opponents in a dispassionate curb stop, there's not much that Cap or WS could have done about it.