"If you compare West Ham now to West Ham at the start of the season, I think you can see our mark - Gianfranco's mark - on the team."
West Ham's solid passing game backs up Clarke's belief. And he knows how to coach a team to play that way.
He added: "Improving is all about repetition. The players work on how to receive the ball, how to see angles and how to pick a pass.
"We practise every day and, when it comes to Saturday, they know what to do: control and pass.
"Seeing it happen in games is our measure of success. I think we're getting it. We've a lot of improving to do but I think it's starting to come."
That goes for individual players as well as the team, of course. While Craig Bellamy has attracted the headlines and speculation about his future, Carlton Cole has signed a new long-term deal and is in the form of his life.
Clarke was the striker's youth team coach at Chelsea.
"He was a kid back then," he remembers.
"Maybe he's just maturing now. He's understands football better, realises you have to be 100 per cent focused for every game."