If you have a pitcher that's a candidate to be traded - James Shields, Jeff Niemann, Erik Bedard, Hiroki Kuroda or Wandy Rodriguez, for example - things are more likely to get worse than they are to get better. That's because most of the prospective buyers are teams in hitter's parks. None of the teams with the most extreme pitcher's parks - the Mariners, Rays, A's, Padres, Mets, Dodgers or Marlins - are buying right now, and that means your pitcher is likely to wind up in Yankee Stadium, Arlington, the Great American Ballpark, Miller Field, US Cellular Field or some other place where baseballs tend to fly into the seats. The presumably better run support will help - as will not having to face that team's offense any more - but if you're a Shields owner, you'd probably rather the deadline come and go uneventfully. One notable exception might be Jeremy Guthrie of the Orioles who's pitching in the brutal AL East in a roughly neutral park. A trade to the Cardinals or even the Brewers (though their defense is abysmal) would be an upgrade.
On the other hand, things could get a lot better for B.J. Upton, David DeJesus, Coco Crisp, Ryan Ludwick, Josh Willingham or any other poor sap trapped in a cavernous, pitcher-friendly expanse.
The Rangers should deal for B.J. Upton. The Rays have already called up Desmond Jennings, and Brandon Guyer is ripening on the vine at Triple-A, so Upton would likely be available for the right price. The Rangers don't have a legitimate defensive center fielder who can hit, and Upton, who's under contract through 2012, would be an immediate offensive and defensive upgrade. Moreover, the park and lineup would likely boost Upton's stats significantly.
The Yankees should deal for Ubaldo Jimenez. It remains to be seen what it would take for the Rockies (who are built to win for 2012 and are by no means a long-term project) to part with Jimenez who's under contract through 2012 with club options through 2014. But the Yankees have $200 million invested in a club that's almost sure to make the playoffs, but woefully thin beyond C.C. Sabathia for the postseason's short series. If they have to include Dellin Betances and Manny Banuelos in addition to a mid-level player or two, they should. As a hitting prospect, Jesus Montero might be a surer thing, but even he should probably be on the table for Jimenez. (The team was willing to move him for Cliff Lee last year, and Montero's had a bad season in 2011).
After last season's .276/.361/.498 line as a 23-year old while playing plus defense in center field, Colby Rasmus should be borderline untouchable. But he's slumped badly this season and has already lost playing time to John Jay. It's hard to know how much a change of scenery would benefit Rasmus, but the talent is there, and it wouldn't be surprising if he were available at a discount given his strained relations with the team.
I hope the Giants don't trade for Carlos Beltran and clog up their outfield even further. As it stands, Aubrey Huff's contract forces them to play top prospect Brandon Belt in left field, and they've already got two center fielders (Andres Torres and ostensibly Aaron Rowand), defensive whiz Nate Schierholtz, Cody Ross and Pat Burrell. Unless Beltran could still play center (a dubious proposition given the condition of his knees), his addition would solve a problem they don't really have. On the other hand, even if Jose Reyes isn't available (as the Mets allege), getting a shortstop like the Mariners' Brendan Ryan - a defensive superstar who has hit for average in the past - would be a significant upgrade at much lower cost.