Sure, his OBP is not impressive overall. But let's look at the splits.
2008: .238/.273/.484, 14 HR in 267 PA
2007: .256/.308/.462, 10 HR in 253 PA
2006: .247/.299/.498, 12 HR in 244 PA
On the road
2008: .258/.325/.547, 18 HR in 252 PA
2007: .276/.329/.453, 7 HR in 207 PA
2006: .276/.348/.451, 8 HR in 276 PA
Mike Jacobs has played for three years in a sinkhole for offense. Dolphins Stadium sucks for Baseball and nobody ever goes there to watch games. Putting the Marlins games in a cemetary would be more encouraging to the players.
Kauffman Stadium is a stadium where one is able to actually fare well with hitting the ball. Plus, I think that the renovations will help since the wind won't blow in as easily due to the new structures behind the fences.
Anyways, it's not like we gave up a great outfielder for a lousy shortstop. Leo Nunez is expandable like a lot of relief pitchers are.
If Mike Jacobs puts up 30 homers, a BA over .270, and even around 40 walks.. then we are clearly better. Especially if Jacobs leads to Dayton giving up on Ross Gload. How does that sound?