It helps that Abomination has effectively pinned himself partway inside the floor. The whole Raft is triple-hulled, and the frames between floors are no exception. There's a lot of material he's punched through, concrete and steel arranged like the layers of an exceptionally ominous cake, and Steve has managed to catch and engage him before he's emerged onto his feet. So he's waist-deep in rubble and lacks the use of his powerful legs as leverage.

That may be one of the major reasons Steve hasn't had his rear handed to him as of yet. That, and the close quarters give Steve more maneuvering room than the giant monster just in general. And Steve knows that, knows his advantage might be fleeting here, and he's going to do his damnedest to keep Abomination stuck where he is. He's clearly doing some damage, but he's pretty tapped out from previous fights, as well.

When Tony moves to push past, Steve flings his weight forward as hard as he can, trying to make sure Blonsky is engaged with him. "Go, go, I'll catch up," he yells back.

Neither of them included the alarming bony spikes the monster has in their calculations, though, and at this crucial moment, he manages to swing one elbow in and catch Steve across the hip with one, wringing a brief yell of pain from him. It's a gouge, a nasty one, and Steve is awfully happy to be immune to tetanus because who the hell knows where those elbows have been? His counterblow goes right for Blonsky's throat, because this is no time to play nice. Still, it's going to take him a minute to disentangle himself and catch up. He can't just cut and run, or he'll get grabbed by the leg and smashed against the floor like a certain deceased god of mischief.