I think it's too early to get excited about the Saito deal. I agree that it's a smart signing, but it remains to be seen if he'll contribute next year. He suffered a serious elbow injury that under normal circumstances would have required Tommy John surgery. Since he's so old, Saito declined it and went with some sort of experimental injection, that allowed him to pitch.
Again, it's low cost / low risk / moderate reward, so it makes sense. I doubt he's a difference maker, though, which unfortunately is the case with all of the Sox signings so far. I'm all for the low cost experimenting, but a blue-chipper would be nice, as well.