Young completed his switch to Old Trafford on Thursday, and Delph believes the men he left behind will miss his pace, skill and impressive work-rate.
"It happens all the time, it's football," Delph told the Birmingham Mail. "People come and go and you have just got to deal with it and just keep going.
"I don't think he could be replaced, to be honest with you. His all-round work ethic was absolutely unbelievable. He must have run twice as much as most people on the pitch.
"With his goals and assists, it will be very hard to replace him - but if we can get somebody here half as good as him, then he would still be a great player.
"You get a lot of players who are not selfish, but do more of their work in the attacking half of the pitch, whereas Youngy is up and down, when he's on the right-hand side especially, working hard for the boys.
"The lads appreciate that from a winger who has flair, but still wants to graft.''