LONDON — After advancing in the men’s doubles at Wimbledon on Thursday, Jack Sock finally discussed his opening-round singles defeat and the fine that followed. On Tuesday, having earned a two-set lead against 81st-ranked Matteo Berrettini of Italy, Sock fell to a 6-7 (5), 6-7 (3), 6-4, 7-5, 6-2 loss.