The Kansas City Royals' offense has been good this season, but they've gotten less from second base than any AL team, something they addressed with their acquisition of Ben Zobrist. Oakland probably wasn't going to make Zobrist the qualifying offer to get a draft pick, so landing one of the Royals' top five prospects (albeit one with a couple of major red flags) plus a second arm is a reasonable return.
Zobrist has been one of the most productive position players in baseball for several years now, since a swing change after he was traded from Houston to Tampa Bay turned him from a near-zero-power guy into someone who averaged 14 homers a year with the Rays, along with patience and above-average defense at multiple positions. He hasn't been that player this year, now 34 years old and playing four months in a strong pitchers' park, although the plate discipline remains superb. But even this reduced version of Zobrist is a mammoth improvement over the black hole the Royals have had at second base this year, as the Omar Infante contract has been every bit as bad as expected -- he's been barely above replacement-level over the year-plus since the Royals signed him. Zobrist is at least a win better for the rest of this season, possibly more if his defense at second base bounces back with the move to K.C., where he'll be playing between an excellent defensive shortstop and an excellent defensive first baseman too and thus may have less ground to cover.