Spring training starts tomorrow with replacement players pretending to be the real baseball teams, while the owners and players union engage in fantasies of their own. Testifying before a Senate subcommittee today, acting baseball commissioner Bud Selig admitted for the first time that the strike has hurt the teams financially. Though ticket sales and television and radio broadcasting rights for 1995 have plunged, Selig said the owners have no choice but to maintain their tough stance in negotiations. Many teams, he said, could not survive another season under the old contract. It remains to be seen how well they can do without the high-priced talent.