The Manchester City boss said: "As far as I'm concerned, in the past and now, Tim Flowers is the best goalkeeping coach in the country.
"We're very, very disappointed to lose him, but he's had the opportunity to join Coventry as assistant manager. It's a step up from a scenario where he was purely a goalkeeping coach at our place and a very good one. He was a good member of staff and an absolute credit to the Football Club.
"I'm desperately sad to lose him, but I've got to respect his wishes and realise that it's an opportunity for him. It's the club he supported as a kid and is nearer his home having commuted everyday from down there.
"He just felt having spoken to him over a few days that it was an opportunity that he couldn't turn down, even though we tried our best to keep him with us."
Flowers is Kenilworth born and played for Kenilworth Wardens. A City supporter,he made five appearances for the Sky Blues and could have signed full time but refused to drop his wage demands.