WIMBLEDON, England — She took aim at the last tennis ball, she slipped, she whiffed, the crowd groaned, and the freshest story of this Wimbledon tournament was over. Jennifer Capriati was out after four rounds. You think she was angry? You think she was down? She came into the press room wearing an MTV T-shirt and beaming from ear to ear as if she had just won the lead in the school play. Which, come to think of it, she sort of has.