I don't really see how you can argue that Beltre is the kind of player that will age badly. A number of these points have been made by other batters....
His age is clearly legit, as proven by the Dodgers scouting scandal. Third baseman tend to age well, for whatever reason; maybe it has something to do with it being an instinct-based position. He is neither a big masher whose weight will quickly catch up to him, nor is he a speedy slap hitter who will suck once he's slower. He seems to be the kind of player obsessed with conditioning and athleticism. And there's not really any evidence of a decline yet. Last year, he had a .329 OBP after returning from surgery to remove bone chips in his shoulder (compared to a .317 norm during his Seattle tenure). His UZR/150 last year was 21.0 and was 15.7 in 2008 (compared to his career norm of 13.9).
In the realm of free agents, there really isn't a better situation than an extremely athletic 30-year-old who will likely only get a 3-year deal.
