Call them depleted, pedestrian, new and unimproved. Whatever adjective best describes the Yankees who, entering Monday, have a major league-high 13 players stored on their injured list. But pump the brakes on rendering them hopeless. It's only April, plus the latest odds and figures imply they're capable of treading water until reinforcements arrive. With wins in five of their last six games, the Yankees embark on a nine-game, three-city West Coast trip with an 11-10 record (2nd place in AL East standings). And