Thomas feels Millen has made a positive impact.
"Keith deserves a lot of credit," Thomas told the South London Press. "He'd have my backing but he's made it clear that where he is at this moment in his career means he doesn't want to throw his hat in the ring. You have to respect that.
"It has fallen in his lap and he has done well. It's not like he has taken over and kept everything as it is. He has changed the training sessions to be a lot more short and sharp. More intense. That benefits my game and I've enjoyed them.
"We've been improving every week from the Arsenal game onwards.
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