Gary Sheffield had only one team on his wish list as last season wound to a close, though he dared not disclose it. Assuming the Yankees would fail to pick up his $13 million contract option, Sheffield had every intention of playing for the Red Sox this year. ?Boston was my first choice,? Sheffield said yesterday before his new team, the Detroit Tigers, lost, 7-6, to the Red Sox in Grapefruit League play. ?But things happen for a reason. Sometimes you don?t get to go where you wanted to go.?