You can't blame this collapse totally on Beane trading away Cespedes. What was so special that he was doing in Oakland that made him this feared hitter? He's not even the 2012 version of himself anymore. The guy was slugging only .464 and his on base was ******* .303. You know how pathetic that is for an alleged star offensive player. You're talking about a guy with little plate discipline and an atrocious eye at the plate. And the worst part? His contact rate has actually risen in Boston and he's still been a bad player. The offense in Oakland was not clicking because of him. They built their offense on OBP guys and guys who can make elite contact. They tossed that out the window starting with Norris, Moss and Jaso. Norris and Moss started striking out like crazy trying to pull everything they could and the trio just stopped hitting fly balls.
The guy had a .767 OPS, he's not the sole reason the team is falling apart offensively.