"You know what you're going to get with Beckham," Waddle told The Sun. "He's not going to get to the byline anymore but his free-kicks are still very good.
"Bentley is a similar player but has energy and will probably score more goals than Beckham. He is someone who we'll be looking at for the long-term and I'm sure he will get his opportunity. But if he's going to be picked he needs a run in the side.
"I think he needs to know that he's going to play three or four games and then we'll see him relax. He's a young player who has come into the squad and is fighting for a spot but I believe he has tried too hard.
"I think that has cost him a bit and that's why he's not an automatic choice yet. But Beckham is getting on a bit now and he's not the player he was."