Morrison was once touted as a potential Manchester United star of the future but his indiscipline off the field led to him being released by the club and signing for West Ham.
The 21-year-old is on loan from the Hammers at Loftus Road, where he has scored six goals and could write himself into club folklore by helping them to promotion back to the Premier League via Saturday's play-off final against Derby County.
"I've known Ravel since he was young and obviously we've both gone our own ways, but since he's come here I've noticed a big change in him," said Simpson.
"He's growing up, maturing and starting to realise the potential he has got. He's one of the best young players I have seen with the ball at his feet.
"Everyone knows his ability but I think he has surprised a few people with his character and his attitude. Maybe it was good for him to move away to different clubs.
"He's looking forward to the final, it's a big occasion for him."
Simpson himself was once on the books of Manchester United before a move to Newcastle United - where he made 137 appearances - and a switch to Rangers.
He played in the Champions League at Old Trafford but insists beating Derby in the play-off final this weekend would be the high point of his career.
"I made my Manchester United debut as a kid and played in the Champions League for them but this will be the biggest game I have played in and if we get through it will be the biggest achievement," said Simpson.
"I've never played at Wembley and I think everyone who follows football knows how big this game is, and if you get through it what it means to everyone.
"I'm trying not to think about losing and spending another year in the Championship. We are just concentrating on the job we have to do.
"The whole squad knows the task ahead of us, we are all together and we all want the same outcome so we will give 100 per cent to make sure we get Premier League football.
"I think we would be the first to admit, if we don't go up, that it will have been a disappointing season. We've got Premier League players who have played at the highest level.
"The reason I came to QPR was the because of the project to get back there, and we have got one game to go. We are all ready to go out and perform in the one game to get us back to the Premier League."
Watch QPR take on Derby live from Wembley as part of Sky Sports' 'Ultimate Weekend' from 2pm this Saturday on Sky Sports 1HD