Thor and Iron Man were not fighting 100% and just straight up didn't use their most powerful abilities and advantageous tactics.
- Thor didn't use a lightning cloak to help keep Thanos at bay nor did he use it to amp his hits or prevent Thanos from snatching his weapons, moments when they would grapple would piss me off, stop playing tug of war and electrocute him
- Thor would not summon sky lightning at all, even in life or death situations like the retarded moment when Thanos had him pinned against a rock somehow struggling to stab into Thor who should logically not even be able to resist "Thanos strongest muscles in the universe".
- Thor's most powerful combo charged lightning sucked and was no where near the size or power as his previous showings
- Iron Man is at his best at long range and is supposed to be a genius aided by an A.I yet he stupidly charges at Thanos in melee with a blade he knows good damn well can't even pierce Thanos
- Not once does he attempt to bombard Thanos with missiles and repulors which were shown to stun and disoriente Thanos before
Iron Man carpet bombing Thanos then Thor pinning him to the ground with a sky lightning blast so Cap can feel relevant by shield bashing him or something before Stormbreaker goes into his chest would be how the battle logically would go. Thousand other scenerios in which they stomp. Thor forgot he could summon the Deus Ex Machina Bifrost?! Use it to send Thanos to the sun, if he "jumps" out he just ends up drifting in space or a slave on Sakaar.