I'm not too broken up about letting Beltre walk.
He's going to be 32 years old and has a career OBP of .328. I think he's a guy who is likely to decline, and there's no guarantee that the player we see next year is the same guy we saw last year.
Also, in terms of the prospects going out in this deal, we'll get a chance to replenish the farm a bit by letting Beltre walk. We're looking at either a 1st and a sandwich pick, or an early 2nd and a sandwich pick. That's not such a bad thing.
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Over on SOSH, one of their more vocal posters is suggesting keeping Beltre, and moving Youk to left. He's being pretty much universally mocked for the idea, and I agree it's not a good one. At the same time, it's probably not quite as bad as people are suggesting.