It’s rare that we see a mid-season trade with proven commodities, All-Star-quality commodities no less, at the forefront of a deal. Typically deals like this involve minor-league compensation, and it’s safe to assume that’s what most had expected here, as Boston scratched Jon Lester from his scheduled start on Wednesday and ramped up trade discussions surrounding their free-agent-to-be ace. Let’s take a look at the trade from both sides, and see what the fantasy impact is here as well.

If we weren’t sure that the A’s were all-in after trading away their top prospect, Addison Russell last month to the Cubs for starters Jeff Samardzija and Jason Hammel, then I think it’s safe to say they’re all in now. They enter play today with the best record in baseball, a winning percentage of .617, along with a run differential that dwarfs the rest of baseball at +162 (divisional foe Anaheim is second at +89). They current have a 99.6% chance of making the playoffs, but with Anaheim just 2.5 games back and nipping at their heels, adding Jon Lester should increase their chances at a division title, which keeps Oakland out of the one game Wildcard playoff. It’s also makes them a force this postseason.

The A’s now feature a lights-out rotation lead by a battle-tested ace with a proven track record of thriving in baseball’s biggest moments. Lester’s postseason resume is impeccable. The left-hander cemented himself as a big-game pitcher last October by going 4-1 with a 1.56 ERA in five postseason starts, including twice out-dueling St. Louis Cardinals ace — and 2014 National League Cy Young candidate — Adam Wainwright in the World Series. For a team with aspirations of playing well into October, it’s hard to envision a more impactful pickup. Not to mention that Lester is having his best season yet. He currently owns career-best marks in ERA (2.52), WHIP (1.12), strikeout-to-walk ratio (4.66), ERA+ (155) and FIP (2.62). The 30-year-old now goes from Fenway Park, which is considered a hitter-friendly environment, to O.co Coliseum, where the A’s have the second lowest team wOBA-against at just .274.

A postseason rotation of Lester, Sonny Gray, Scott Kazmir and Jeff Samardzija is an opponent’s nightmare. The fifth spot will be interesting to fantasy owners over the final two months. The newly acquired Jason Hammel has been a disappointment and Jesse Chavez, one of the year’s best surprises, has blown past his previous season high innings-pitched totals, and is showing signs of slowing down. Hammel was hammered by the Astros on Wednesday night, and now has a 9.53 ERA and 2.12 WHIP in his four starts for Oakland. Both pitchers are worth spot starts down the stretch, but I wouldn’t bank on much consistency from either arm. The Red Sox have a number of young arms that are likely to get a look over the next couple months, none of which should hold much, if any, fantasy value for the remainder of the season.

The two big things that the Red Sox lack, from the big-league level all the way down to A-ball, are power bats and outfield depth. Despite having one of the best minor-league systems in all of baseball, the Sox show no signs of power on the way, and their best bats are infielders and catchers. Today’s acquisition of Yoenis Cespedes goes a long way in curing what ails them, at least in the short-term.  The two-time home run derby champion has plus power that should play very well in Fenway Park. The 28-year-old Cuban totaled 49 home runs between 2012 and 2013 and has hit 17 homers in 101 games this season despite calling O.co Coliseum his home. The free-swinging Cespedes owns a career .788 OPS in 365 games, but should see that number improve in Boston. It’s likely that the Red Sox try and lock him up this off-season, as the look to keep him through his prime, increasing his fantasy value in both re-draft and keeper leagues.

Another important piece of Thursday’s deal is that the Red Sox received a competitive balance draft pick — the second pick in Comp Round B — along with Cespedes. For a team that’s stock full of minor-league talent, this is yet another addition that makes the likelihood of a quick turn-around very encouraging for Red Sox fans. The whispers of Lester returning to Boston as a free agent during the off-season, something he himself said he’s open to, only fuels the fire in Red Sox Nation.

The A’s also acquired outfielder Jonny Gomes in the deal, adding a potential platoon replacement with the loss of Cespedes. Gomes should have a similar role in Oakland, as a bench bat that can mash left-handed pitching. The hot-hitting Stephen Vogt looks to be the main beneficiary, as he’s likely to stay in the lineup on most days due to his versatility.

Do the A’s have enough offense left to win the World Series? The 2011 Phillies and the Braves of the mid-90’s have had dominant rotations in the past, and fell short of expectations. Only time will tell. Will the Red Sox bounce back and contend in 2015? Can they keep Cespedes, or perhaps even add Lester this off-season? Again, that chapter has yet to be written. I know that I can’t wait to watch it all unfold.

Follow Ryan on Twitter, @RyNoonan.  You can also find his work at numberFire and hear him weekly on ‘Caught Looking-The Fantasy Baseball Podcast’ for TheFantasyReport.net.