Now that we've all had time to read about and digest the Beltran deal...
On balance, I like it. All three of the prospects are legitimate major league candidates, and perhaps one of them (methinks Buck) has a chance to be a star player. I don't think the Royals could have done any better under the circumstances.
However, I'd like to compare this trade to the fantastic trade Seattle made today. The ChiSox gave up their best prospect (and one of the top 5 prospects in baseball), Jeremy Reed, and a young major league catcher (Olivo) for Freddy Garcia. Reed is a much, much better prospect than Teahan, and Olivo is probably at least equal to Buck. I don't know much about Wood and Morse, so we'll just call that a wash, and Ben Davis is a career backup catcher. Garcia is in his walk year, like Beltran, so they're both three month rentals.
Which player - Beltran or Garcia - woill have the most impact on making the playoffs over a 90 games stretch? Beltran and Garcia were the most coveted batter and pitcher in the trade market this year, and both play at premium positions (CF is crucial defensively). Statistically, Beltran is good for 6 win shares above average (WSAA) so far this year, compared to 2 for Garcia. Beltran has been the more consistent performer over the past few years, so his chance of maintaining performance is higher than Garcia's. Garcia has pitched well this year, but he's been pretty average and inconsistent for the past few years, and I wouldn't call him a sure thing to pick up several wins over the next three months.
I think you could make a strong case that adding Beltran to the Astros will be more valuable than adding Garcia to the White Sox for the rest of the season. If the ChiSox make the playoffs, Garcia will be more important than Beltran, because pitchers have a greater impact in the postseason. Overall, being conservative, its reasonable to say that Beltran will be at least as important to Houston's playoff chances than Garcia will be to the White Sox.
So why did Seattle make out so much better than the Royals? In the past, the answer would have been fairly easy - Allard Baird and Royals ownership have no idea what they're doing. But this time, I think the Royals/Astros/A's made a RATIONAL trade, while Chicago/Seattle made an IRRATIONAL trade, owning to the dynamics of the irrational player marketplace. The White Sox overpayed dearly for Garcia on paper, who is seriously overvalued because he's the only available above average pitcher in the trade market. But they may have felt they had no choice, given that other teams were probably willing to give up their top talent to land Garcia as well (but there are few prospects like Reed).
The market is what it is, but Chicago has rented a slightly above average pitcher for three months instead of enjoying a highly talented hitter anchor their outfield for the next seven years. The Royals gained three good prospects, but all have question marks. Its certainly possible (though not probable) that none of these players will turn out to be much. But its an acceptable risk.
I'm happy for the Royals, but the player marketplace is screwy: Seattle can trade a pitcher like Garcia for a Grade A prospect, while the Royals only get back B prospects for the one of the players in the game.