And while the 24-year-old is behind Danny Care, Ben Youngs and Lee Dickson in the England pecking order, Wasps boss Young has no doubt who he'd rather have in his side.
"If you're looking for somebody who's going to create something from nothing, there's not many better," said Young, after Wasps jumped to fifth in the Aviva Premiership table with a 34-15 success.
"I don't see many other scrum-halves scoring that type of try. He's got real wheels.
"He found a way to get to the line and that was probably the turning point of the game. It was a fantastic solo effort.
"His kicking game is as good, if not better, than any other scrum-half in the Premiership, his service is as good and he's making the right decisions for us week in, week out.
"I wouldn't swap him for anyone else."
Simpson hasn't added to his solitary England cap that came at the 2011 World Cup but Young says he's playing the best rugby of his career.
"He's getting better and better with every game," added Young.
"He hasn't let us down at all this season, he's been outstanding.
"He's certainly not lacking much as a rugby player. He's got everything in his locker.
"It could have been that we put too much responsibility on him in the past. We've diffused that a little bit by getting other people involved and we're not looking for him to make all the calls."