By Dan Marsh Marco Silva believes that failing to make the most of the opportunity to strengthen in the transfer window is “a problem” after Mikel Arteta hinted Arsenal could keep their power dry in January. The Gunners were at the Premier League summit on Christmas Day but will spend New Year’s Day in fourth after back-to-back defeats against West Ham and Silva’s Fulham, who beat their London rivals 2-1 at Craven Cottage on Sunday. Prior to the match, Arteta was coy about the upcoming winter transfer window – and he appeared to hint after the match that Arsenal would not be as active as previ…