And the Angels' shrewd early-May acquisition of Padres reliever Ernesto Frieri -- an All-Star Final Vote candidate -- demonstrates that it's not always the most high-profile pickup who makes the biggest impact. We also saw that last year, when the Tigers' relatively under-the-radar trade with Seattle for Doug Fister signaled the start of their sizzling stretch run.With all this in mind, here are the 10 biggest buzz topics as the swapping season begins: 1. Bartering with the Brew Crew: Because the injury-addled Brewers are fourth in the NL Central and Zack Greinke and Shaun Marcum are mere months from free agency, Milwaukee could be a source for starting help. Greinke is in the midst of another elite season and would seemingly have no incentive to give the Brewers a big discount on an extension. 2. Phillies face the facts: Now 11 games back in the NL East, the Phillies sure look like definitive sellers, and the Thome trade to the Orioles could be just the beginning. With an aging and expensive roster getting, well, older and more expensive, and Cole Hamels approaching a major free-agent payday, it's possible Hamels can be had in the trade market. And what a boost he would be for a contending club. Shane Victorino could also be put in play. 3. Theo makes his mark: As explained in this piece , Theo Epstein's Cubs have an opportunity to accelerate their rebuilding by dealing the likes of Matt Garza, Ryan Dempster, Alfonso Soriano and Paul Maholm. The Cubbies should be active. 4. Astros open for business: First-year general manager Jeff Luhnow can be of assistance to contending clubs looking for help in the bullpen (Brett Myers, Brandon Lyon), rotation (Wandy Rodriguez) or lineup (Jed Lowrie). And while Lee is obviously available, this weekend's developments showed that he takes his no-trade clause seriously. 5. Padres could provide power: The market seems like it could be particularly ripe with pitching talent, but there might be few impact hitters to be found. That's what makes Carlos Quentin particularly appealing. The Padres will have to decide whether to lock up the hometown talent or take advantage of a seller's market. 6. Twins could tear it down: The healthy returns of Joe Mauer and Justin Morneau haven't gotten the Twins on track, and it might be time for Minnesota to consider parting with free-agent-to-be Francisco Liriano, who has pitched well of late, or Denard Span or perhaps Josh Willingham, whose value might be at its peak right now. 7. (Potentially) no shortage of starters: It's difficult to separate fact from fiction at this stage, but it appears that contending teams in need of a new look in their starting five should have some options. You have the potential for an elite injection if Greinke or Hamels are available, and you have veterans like Dempster or Seattle's Kevin Milwood, who could help. San Diego's Edinson Volquez might get moved, and the aforementioned Garza, Marcum and Rodriguez could all help a team. We might also see a team like the Nationals, which is strong in the starting department, deal from a position of depth (Chien-Ming Wang or John Lannan, perhaps) to improve elsewhere. 8. Closers for hire: Relief help is always in order this time of year, and, in addition to Myers, some other late-inning options with closing experience who might be available are the Royals' Jonathan Broxton, the Padres' Huston Street, the Brewers' Francisco Rodriguez, the Twins' Matt Capps and the Rockies' Rafael Betancourt. 9. New on the "buy" side: The Pirates and Indians notably crossed the line from sellers to buyers last year, and both could be in the market for a bat this time around. Two upstart clubs that might follow that formula this year are the Mets, who could use bullpen help, and the Orioles, who have already added Thome and could use an injection of quality starting pitching. 10. Anybody desperate to deal? It's a question to which the answer will evolve over time. But in the NL, the currently reeling Dodgers and their new owners have particular interest in making a push, and in the AL, we've seen how motivated owner Mike Ilitch is to bringing a World Series title to Detroit, so the Tigers might not pull any punches if there's a rotation, second base or bullpen upgrade to be had.
Anthony Castrovince is a reporter for MLB.com. Read his columns and his blog, CastroTurf, and follow him on Twitter at @Castrovince. This story was not subject to the approval of Major League Baseball or its clubs.