The Yankees, given the state of their pitching staff, had the best chance to land him. That and the fact that they were apparently willing to spend $30 million on a pitcher who is breaking down. He's cheated age for a while, but there's a freason he only pitches four months a year right now.
This whole argument is based in hypotheticals. IF Clemens pitches well, it's a good move by the Yankees. There is just reason to have extreme doubt that a guy switching to a superior offensive league and who can't pitch more than 6 innings will be successful. There's just reason to have extreme doubt that he will not perform in the ALE. There's just reason to have extreme doubt that he will be worth such a steep monetary investment, especially with the luxury tax.
Yes, after this offseason the Red Sox can't cry poverty, but none of the moves have the risk this one does, IMO.