Sacked after just three months in charge, the Manchester United legend has since been named new manager of Plymouth Argyle.
Ruddy told the Fozcast: "Wayne came in and tried to implement a style of play which was more possession-based, more building from the back, with the same players.
"He was always on the pitch - he was more of an overseer.
"I felt like I got on well with him, I had a couple of nice conversations with him. He made it clear he wants to be a manager, not a coach.
"He's not going to be the one setting up the sessions and delivering sessions all the time - he has his backroom staff for that. But he'd dip in and out during the sessions."
He also recalled: "You forget how good a player he was. We're on the training pitch and he's saying, 'No lads, I want you to do this'.
"And he'd take a touch and pick this ball over the top, inch-perfect. You're going, 'Yeah, that's the level you're used to. We're not quite there'.
"His footballing brain is so advanced because of how he was as a player. It's trying to get that dynamic, when you're someone like Wayne Rooney, that you're not dealing with a team of Wayne Rooneys."