Bullard will play tonight for Hull reserves and Ashbee told the Hull Daily Mail: "Jimmy will make us tick, no question about that.
"When you've got a player of his ability back in the team, he can only be a good addition.
"He says to me every day when we're travelling to training that he feels stronger than he's ever done so it can only be a good thing.
"People will talk about how he's a bubbly character and a joker to have around the place but first and foremost, he's a top quality player.
"The gaffer bought him here because he's a very good player and that's exactly what he is, you don't get picked for England if you're not up there with the best."