What the Pirates get
It's the ideal time to trade Jason Bay. He's closing in on free agency but has a year left of control and is under contract for a good salary. That extra year of control seems to be valued very highly in the trade market right now, given the delta between the return on Mark Teixeira in 2007 and the return on him as a two-month rental in 2008. The Pirates aren't going anywhere this season, but they've added to their stock of players who already can contribute in the majors, or will be able to contribute soon, for the minimum salary. They also have added one high-upside prospect.
Andy LaRoche can -- and should -- be playing every day for a major league club right now. However, the Dodgers have seemed to view him as a shirt they received as a gift and didn't like but couldn't bear to part with, either. Now headed to a team without a capable third baseman, LaRoche should hit for average and post a great OBP, and he'll provide average power and fringe-average defense. He's not a great athlete and isn't a player I'd want to have when he's in his 30s, but for the next four or five years, he should be very good.
Craig Hansen was a first-rounder in 2005 and could have gone in the top 10 had he not demanded a $4 million bonus. That allowed him to fall to the Red Sox, who gave him his money and a major league contract. But although he has a strong arm, poor command and a stiff delivery have led to bad performances in the majors. He typically throws 93-96 mph and flashes an outstanding slider, but for every good slider he throws, two back up on him. He has an above-average changeup in the upper 80s with good fade, but he rarely uses it. The Craig Hansen I've seen endless times in Boston isn't a big league pitcher, but he's worth a shot.
Brandon Moss should slot in as the everyday left fielder in Pittsburgh, but he projects more as a quality fourth outfielder on a good team. He has fringe-average power and plate discipline, and would be an everyday player if he could play center, but his bat doesn't quite profile like an everyday corner outfielder's. He probably will need a right-handed platoon partner if the Pirates want to play him every day against right-handed pitchers.
The one real upside player in the deal is Bryan Morris, who is in his first full year back from Tommy John surgery and already is pitching well in low-Class A ball. Morris throws 90-96 mph with a potential curveball out pitch and a sharp two-plane breaker with good depth. He's still developing his changeup, and his command also is improving but still below average. He throws slightly across his body, which could lead to arm injuries (and could, in theory, be part of why he blew out his elbow in the first place). The Dodgers have been working with him to try to minimize that, though. In a perfect world, he'd be a No. 2 or No. 3 starter, but if the arm problems recur, he might be a dominant late-game reliever.
The Pirates have been quietly stocking players who lack upside but can contribute at the big league level for the minimum salary. At some point, they'll need to inject some star-caliber players, but in the meantime, it's a sound strategy to field a competitive team without wasting money on "proven" veterans. And because no team was willing to surrender an impact prospect for Bay, it was smart for them to take the best offer available now rather than to try to play the market again in December when Bay's value would have declined again.
What the Red Sox get
The Red Sox get slightly worse for this year but suddenly look much better for next year. Bay is a definite short-term offensive downgrade from Manny Ramirez, and although he has power and plate discipline, he's been doing it against inferior pitching in the National League and is a small step down from a full-strength, not-mailing-it-in Manny at the plate. But he's a better fielder, as Manny consistently has rated among the worst left fielders in baseball, and Bay is less likely to have a Jason-being-Jason day off or to fail to run out a key ground ball.
Bay will really improve the 2009 Red Sox. Boston was almost certain to decline Ramirez's $20 million option for 2009, which would have left the Red Sox with an offensive hole to fill for next year. Bay is under control for next year, so the hole is already filled, and he's signed for an amazingly cheap $7.5 million. Even considering the $7 million Boston sent L.A. to pay Manny's freight for this year (because the Dodgers told teams they could not add any payroll this season), the Red Sox are getting a $15-20 million bat in Bay without the headaches Ramirez had caused lately. And they managed to do it without depleting their strong farm system or committing to a four- or five-year deal they'd regret by the middle of the second year.
What the Dodgers get
The Dodgers get much better this season in exchange for a great young arm who is probably three years away and a third baseman on whom they appeared to place little or no value. You have to imagine this is seen as a huge win within the L.A. front office.
If Ramirez, now freed from the team that "doesn't deserve" him, stops mailing in various at-bats and hits toward the right-tail end of his abilities (as he hit in April, for example), the Dodgers have just made a quick two-win upgrade in exchange for a good player they weren't going to use and a quality prospect, and they didn't have to add to their payroll. The move keeps Juan Pierre and Andruw Jones on the bench where they belong, and I wouldn't be surprised if the team were to try to outright Jones off the roster and assign him to Triple-A to clear the roster spot. The move makes the Dodgers slight favorites to win the NL West, assuming they put the right personnel on the field.