A three-team deal that sent Jake Peavy to the Red Sox, Jose Iglesias to the Tigers and a host of prospects to the White Sox was easily the most significant trade of the season up to that point. 

The move, which upgraded the Red Sox pitching staff to one of the most impressive in Major League Baseball, suddenly put pressure on the rest of the American League contenders to get serious about roster considerations going into the final run of the regular season.

Boston was considered strong, despite relinquishing the AL East division lead to the Rays recently. Red Sox general manager Ben Cherington told reporters in an overnight conference Wednesday morning that this move was about ensuring the Sox are in position over the next two months to compete for a playoff spot.

It’s no surprise that Boston would be concerned with remaining viable, considering the pennant arms race with the Rays and Orioles. Apparently, the Yankees play in that division, too.

Peavy adds to a pitching rotation that already features Jon Lester, John Lackey, Ryan Dempster and possibly a healthy Clay Buchholz at some point down the stretch.

Teams like the Orioles, A’s and Rays may not be scrambling, but please believe they’re all on notice.

Peavy isn’t the ace he was when he won the 2007 Cy Young Award with the Padres, but even with a putrid White Sox squad this season, he’s logged a solid 8-4 record, 4.28 ERA and 1.138 WHIP.

SB Nation’s Red Sox blog Over the Monster had this nugget on the trade:

“(Peavy) is overqualified for the role the Red Sox have him in, which is essentially to fill in for Clay Buchholz for the next month and then settle in as the club's third or fourth-best pitcher, depending on which versions of Jon Lester and Felix Doubront show up. He's under contract through 2014 as well, so, if he's healthy at the end of the deal, the Red Sox will, in theory, be able to submit him a qualifying offer and earn a compensatory first-round pick if he signs elsewhere. Even if he's only a little above-average, if he can stay on the mound, he'll earn his check.”

Meanwhile, the Tigers are anticipating Jhonny Peralta’s 50-game suspension in connection to the Biogenesis scandal to be handed down any day now.

Multiple league reports indicated earlier in the week that players who had not been suspended for PED violations would agree to the 50-game suspensions by Friday, including Peralta. Iglesias is considered a defensive upgrade at shortstop, which means the Tigers at the very least should keep the ball rolling as the preeminent team in the AL Central.

These are teams we expect to see in October, and last-minute trades like this one are directly connected with that expectation.

The extra Wild Card spot makes the postseason pursuit a double-edged sword for teams that have success for most of the year, especially in the American League. Everyone wants to make it to the playoffs, but the really good teams are looking to avoid that one-game Wild Card showdown at all costs.

And if they do find themselves in that situation, there can’t be a weak link in the pitching staff that the season relies on.

It’s go hard or go home.