On the non-waiver trade deadline on July 31, the Oakland Athletics acquired left-handed starting pitcher Jon Lester and outfielder Jonny Gomes from the Boston Red Sox. Just hearing this tidbit of the trade that day would give Athletics' fans big jitters, but the next piece of the trade is what might have changed everything. In return for Lester and Gomes, the Red Sox received Cuban outfielder Yoenis Cespedes.

If someone were to have asked that day: "Who was the winner of the Red Sox-Athletics trade?" The answer most likely would have been the Athletics. For those who answered that question with "Oakland," they were wrong.

The Athletics did pick up a left-handed hurler who is dominant during most of his outings and a valuable bat off the bench that can provide you with some innings in the field, as well. Yet the Athletics gave up what was undoubtedly their biggest piece in their once-thriving offense: All-Star outfielder Yoenis Cespedes.

Cespedes alongside All-Star third baseman Josh Donaldson were the heart and soul of the Athletics' offense, as they managed to rack up a 59-36 record during the first half of the season. At the deadline, general manager Billy Beane wanted to out on the market and acquire even more starting pitching, even after they had made a deal to acquire right-handed pitchers Jeff Samardzija and Jason Hammel from the Chicago Cubs. The only way they could possibly get an ace like Lester into their rotation was to give away their cleanup hitter in Cespedes.

Cespedes has gone on to thrive even more in Boston, hitting .268/.293/.433 with four home runs, 28 runs batted in and eight doubles, along with three outfield assists in 37 games. With both the Athletics and the Red Sox, he has compiled a .329 wOBA, 112 wRC+, a career-worst .197 ISO and a career-high 3.5 WAR. Let us not forget that Cespedes is also the two-time defending champion in the Home Run Derby.

Up until July 30th, the Athletics had been scoring just over five runs per contest. From then until September 11, the club has only scored 3.7 runs per game.

Brandon Moss, Jonny Gomes, Sam Fuld and Craig Gentry have all started in Cespedes' left field spot and have combined to hit .200 with no home runs and only two extra-base hits in 130 at-bats, as of September 11. Moss, Gomes, newly-acquired Adam Dunn, Derek Norris and Stephen Vogt have filled in at the cleanup spot and have only managed to hit .206 with two homers, both of which were hit by Dunn, in 136 at-bats, as of September 11.

On the contrary, the Athletics need to resurrect the offensive mojo they had in the first half of the season and start hitting the ball again. Even though Lester has a sub-three ERA since being acquired from the Red Sox, overall, Boston won this trade because not only do they have team control of Cespedes until after the 2015 season, but they can potentially re-sign Lester during this upcoming offseason, as it is very unlikely that the Athletics sign him back this winter.