That leaves the second option. Two words; Jermaine Dye.
At this point, signing the 36-year-old right hander is nearly a no-brainer. For the next month, Gardner is moving back to center field no matter what. And Nick Swisher will be more than adequate in right, especially if he keeps up his current offensive pace (.282 avg, .371 OBP, 15 RBI). But a platoon of Winn and Thames will not be sufficent in left field if the Yankees expect to win a championship.
Yes, Dye had an down season last year. He hit an embarrassing .250 and only managed 27 home runs and a meager 81 RBIs. But even that futile output was still better than Thames (.252/13/36) and Winn (.262/2/51). This is not to degrade either of those players. Both were signed as role/platoon players and both should remain servicing the Yankees in that capacity. But New York needs another bat in the outfield now before the ghost of Babe Ruth comes after Robinson Cano to reclaim his bat.
And down the road, the Yankees will need a powerful right-handed bat off the bench and occasionally in the DH role (at the very least). The New York brass have made it clear that they are staying "economical" going forth, but something tells me Brian Cashman could find a way to work the free agent Dye into their budget when he balances his likely contract against the revenue generated from a 28th championship. Joe Girardi's predecessor Joe Torre's teams were frequently complemented by aging outfielders like Darryl Strawberry, Chili Davis, and David Justice. Dye could be Girardi's Strawberry and one need only ask the last-place Dodgers manager how valuable a player like that can be to a championship season.