Oakland general manager Billy Beane acted boldly, trading top prospect Addison Russell in a deal that brought starters Jeff Samardzija and Jason Hammel to the Athletics.
Then it was Jerry Dipoto's turn. The GM of the Los Angeles Angels acquired closer Huston Street on Friday night, giving his team another option in the late innings and adding more intrigue to an already-spirited AL West race. The A's have baseball's best record, but the Angels are only 1 1/2 games behind, and both teams have aggressively improved themselves with major trades since the beginning of July.
That's just the beginning, of course. With the trade deadline coming up at the end of the month, several big names could be on the verge of switching teams during what is annually one of baseball's most compelling stretches of the season.
The A's and Angels have already made big moves. Here are five more ways the trade deadline could affect this year's postseason races:
DETROIT'S BULLPEN: Joe Nathan is still testing the Tigers' patience with a 6.06 ERA, and whether he holds onto the closer role or not, Detroit's relief corps could use a boost. Street has been traded to the Angels, but Philadelphia's Jonathan Papelbon is still out there - and having a fine season.
Trading for Papelbon would be a fairly audacious move for a Detroit team that spent so much to bring Nathan in last offseason. Joakim Soria of Texas is another relief alternative who could fit in well with the Tigers - and perhaps a more realistic target.
ROTATION HELP: The New York Yankees are barely above .500, but they trail first-place Baltimore by only three games in the tight AL East. With CC Sabathia out for the season and Masahiro Tanaka dealing with an elbow injury, the starting rotation is an obvious area of concern.
Philadelphia's Cliff Lee is set to come back from a strained left elbow and could be dealt shortly thereafter. Tampa Bay's David Price is having another impressive season, but the Rays are playing much better of late and now trail the Orioles by only 7 1/2 games. Does that mean they could hold onto their ace and try to make a postseason push of their own?
LONG TIME COMING: Kansas City hasn't made the playoffs since 1985. Seattle has gone over a decade since its most recent appearance, in 2001. Both teams are in the thick of the race for the American League's two wild cards - but the Royals and Mariners also have their flaws.
The Royals have the fewest home runs in all of baseball, and pretty much any significant bat would boost their playoff hopes. Minnesota might be willing to part with free-agent-to-be Josh Willingham, who is mired in a horrendous slump but still draws his share of walks. Willingham, who hit 35 home runs in 2012, would be a relatively low-risk target for any team trying to add power without giving up too much.
Willingham could also be a good fit for Seattle, which could use some more pop in the outfield. Alex Rios of Texas is another outfielder who could be traded.
FLEXIBILITY: Cincinnati is three games out of a wild card despite injuries to Joey Votto and Brandon Phillips. General manager Walt Jocketty says he wants to add a hitter who can play multiple positions.
The obvious fit, then, would be Tampa Bay's Ben Zobrist, who can play second base, shortstop and the outfield. Of course, that's a moot point if the Rays don't end up selling.
PHIRE SALE: The Phillies are 11 games out of first place and have several players who could be attractive to other teams. It's not just Papelbon and Lee. Middle infielders Jimmy Rollins and Chase Utley, outfielder Marlon Byrd and right-hander A.J. Burnett could all be of help to teams in contention, meaning this could be a busy couple of weeks in Philadelphia.
STAT OF THE WEEK
San Diego rookie Odrisamer Despaigne lowered his ERA to 1.31 on Sunday, when he had a no-hitter broken up in the eighth inning against the New York Mets. The 27-year-old Cuban signed as a minor league free agent on May 2, and he had a 6.03 ERA in seven minor league starts.