Summerville fired in an impressive hat-trick for the Under 23s against Crystal Palace on Monday night, as Marsch looked on from the stands.
Not for the first time in recent weeks, Marsch was impressed by the young Dutchman’s performance in Premier League 2 competition.
“I thought he played fantastic,” said the American.
“I think that he is doing a great job in the matches, showing that he is learning more and that he is more prepared and that we can count on him more and more.”
He added: “I think that he has grown since I have been here more and more and more.
“I have talked to him about his behaviour and mentality and professional behaviour every day off the pitch and what he needs to be like when he shows up here, what what the work week needs to look like and then how to adapt to the style of play that we want and how to continue learning the tactics and behaviours.
“And for me he has grown a lot in the last month and I think this performance is a representation of his professional behaviour, his work ethic, his mentality to try to learn and adapt.”
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