You can see it in the way he plays and through him as a person (he's done some very good interviews on skysports). He's aggressive, ambitious and not fazed by pressure.
He had the choice at city to stay on but opted to go for the project at Ipswich and get his playing time, doing very well in the Championship. He didn't change his approach or look remotely out of depth with defenders in the premier league when the step up came. He played his aggressive, direct way and has a clear belief in his ability.
There's a risk with every player when joining United and considering the "step up", but it's quite clear that Delap looks like he'd relish these types of challenges.
Another aspect about Delap is the strengths he brings suits Amorim and pretty much most teams. He's quite a shit house

but he can carry the ball, he's not slow and has no problem taking a shot quickly. Of course Osimhen is probably a bit quicker, he's a better finisher but I don't think he offers anything else more.