The Doncaster fighter – who triumphed in an eliminator for the WBC super bantamweight title last weekend – and his twin brother Jamie began working with Rotherham-based Coldwell last May.
And be believes the improvement in both him and his brother has been stark under Coldwell’s guidance.
“Hopefully people will have seen improvements in me in that last fight and Dave will get some credit because he’s put a lot of time and effort in with us,” McDonnell told The Star.
“Hopefully me and our kid can repay that effort.
“I can see it daily where I’m improving.
“It’s not major or massive, but they’re noticable improvements in each fight.
“There’s always explanations behind what we’re doing and I think it sinks in a bit faster when he shows you and tells you.
“Dave doesn’t let you slack. Even when we’re not in full training, we’re still coming in and having good, hard sessions, learning sessions.
“We’ve never really had that before. He’s whipped up into shape, he makes us realise between camps that you can improve if you’re staying on it all the time and staying focused.
“Dave bring that to the table, keeping us on our toes. We’re always learning and improving and I think it’s something we needed.”
McDonnell put on a masterclass to beat Jorge Sanchez in Manchester last weekend, continuing the strong run of form for Coldwell’s small crop of fighters.
Jamie McDonnell is set to defend his WBA bantamweight title on April 9 at London’s O2 Arena while European cruiserweight champion Tony Bellew is awaiting his next date.
Coldwell has recently welcomed Olympic bronze medallist, heavyweight David Price, into his team.