The former Manchester United midfielder - whose career has been dogged by issues with his off-field behaviour - will complete his move to Loftus Road next week to ensure he is available until the Sky Bet Championship play-off final.
"You need people who can open the door, someone who can unlock a defence," Redknapp told Sky Sports News when asked about the 21-year-old's imminent arrival. "I've always had someone in my team who can change a game.
"I've always enjoyed having someone like that, whether it was Paolo Di Canio or Paul Merson when I went to Portsmouth, someone who can do something special and turn a game for you.
"I just think Ravel is one of those lads who can do that for us. I'm not sitting here saying it's not a gamble because he is a gamble.
"If he didn't have a problem somewhere, he wouldn't be coming to QPR. He would be still at United because he's got that talent.
"It's a chance you take sometimes in life; you have to take a gamble. Sometimes they come off, sometimes they don't - but if you don't buy a ticket, you are never going to win the lottery."
Makes you wonder who he is listening to? Normally Morrison would walk into any Hammers side in spite of what BF Sam might say.- Roman0503