In the end, it's mostly about which teams grab one of the 10 postseason berths. The Red Sox have a different agenda, but their final 53 games will be as interesting as almost any.
OK, so here's a handy dandy checklist...
Oscar Taveras : This is his opportunity. He has been one of baseball's best prospects for three years. Scouts have long predicted he'll be an impact bat if he ever gets a real opportunity. The Cardinals had trouble finding him that opportunity. With the departure of Allen Craig, the Cardinals will write his name in the lineup regularly and hope that he can provide the power they desperately need.
Will Middlebrooks/Xander Bogaerts: There's no way to overstate how important these two guys are to the Red Sox these last two months. If they play well, it'll give the Red Sox confidence that they've got third base and shortstop taken care of for the foreseeable future. If they can't, then GM Ben Cherington has a huge challenge in assembling a competitive roster for 2015. For Middlebrooks, it's partly about staying healthy. He has been on the disabled list three times over the last two seasons. If he can remain on the field, the Red Sox will find out if he can repeat his nice 2012 numbers (.835 OPS in 286 plate appearances). He has a .687 OPS in two seasons since, but injuries have kept the Red Sox from making a true assessment.
Stephen Vogt /Jonny Gomes: Billy Beane's acquisition of Jon Lester was so stunning because of who he gave up. Yoenis Cespedes strikes out too much, but he also might have a 40-double, 30-homer season. That's the kind of power every team tries to have. But Beane believes that the way to build a championship team is to acquire as much pitching as possible and figure things out offensively. In this case, the A's seem likely to go with a Vogt/Gomes platoon in left. Vogt has an .892 OPS against right-handed pitching this season. Gomes has an .831 OPS against left-handed pitching. Meanwhile, Cespedes has an overall .767 OPS. There are power and defensive considerations to take into account, but if the A's can be anything close to similar production as they had with Cespedes, they'll be happy.
Craig: His offensive dropoff has been nothing short of bizarre. He had an .863 OPS 2011-2013. It was .638 at the time the Cardinals traded him to the Red Sox. He's only 30 years old. He's also a serious kid with a relentless work ethic, and the Red Sox will attempt to get him back on track. Perhaps it'll be as simple as a change of scenery. Scouts who've watched him see someone who got into some bad habits, perhaps to compensate for last season's foot injury. As he tried to adjust, he just made them worse. He seems to have become too conscious about outside pitches, but at Fenway Park, he may notice that big tall thing in left field and decide it would be a good place to bang a few off of. The Red Sox made this deal, in part, because they saw no offensive help available in free agency. They're investing heavily in the belief that Craig will lead a Red Sox renaissance in 2015.
Red Sox kid pitchers: Step right up, boys. Your time has come. Anthony Ranaudo won his Major League debut with six solid innings against the Yankees on Friday. Allen Webster, who made seven starts in 2013, is getting an extended look this season. In trading Lester and John Lackey, the Red Sox sent a message that they believe in their kids, not just Ranaudo and Webster, but Brandon Workman, Henry Owens, Rubby De La Rosa and others. They intend to sign one veteran free agent this winter, but it's these kids who'll decide what the immediate and long-term future of the franchise looks like.
Tampa Bay Rays: It's not just about Drew Smyly replacing David Price in the rotation. It's about how the Rays will react to a clubhouse that suddenly is without a huge, vocal, productive presence. What message did the players get when management dealt away the No. 1 starter at a time when the club finally had sprinted its way back into contention? No manager is better than Joe Maddon at getting his players in the right frame of mind. This one is a challenge even for the best.
Ezequiel Carrera: The Tigers acquired the best player on Thursday. But in getting Price, one of the guys they gave up was Austin Jackson, a solid center fielder. Carrera will get a chance to play, perhaps a significant chance. At times, he has looked like a future star. He hit .272 in his second season with the Indians, but struggled after that. He's hitting .307 at Triple-A Toledo for the Tigers and has earned the chance. It's up to him to fill a hole.
St. Louis Cardinals: One year removed from the World Series, the Cardinals are different both in style and substance. To remove Craig and Joe Kelly from the clubhouse and to acquire two edgier personalities in John Lackey and A.J. Pierzynski may say that GM John Mozeliak wasn't exactly thrilled with some intangible things. Whether that was the intent or not, it's what the Cardinals have at a time when they're headed down the stretch in a tight National League Central race.
Chase Headley /Stephen Drew: They're part of the new-look Yankees, the club GM Brian Cashman has changed incrementally the last six weeks. Both are hoping to jumpstart their careers. Beyond that, they're getting the opportunity at a time when the Yankees are scratching and clawing to keep the Orioles within shouting distance in the American League East. Given that both have been impact players at various points in their careers, it's not the longest of stretches to think they've arrived at a perfect place and time.
Pittsburgh Pirates: Trade Deadline acquisitions impact clubs, both substantively and emotionally. The Pirates tried to make a splash. They worked relentlessly to acquire pitching, and apparently offered some nice packages. In the end, though, they will go [for now] with the current group. That's the group that has gone 17-11 since June 28 and cut their deficit in the NL Central from nine games to 2 1/2. If Gerrit Cole can return from the DL (no sure thing) to take a spot in the rotation, the Pirates will have their impact move for the stretch run.