Campana is better hitter when he's batting second in the line up rather than as a lead off man. That's because when a man is on base, Campana's able to take full advantage of his bunting skills to advance the runner while also attempting to bunt his way on base.
Campana is currently hitting .272 with a .308 on base percentage. But as a lead off man, he's only hitting .226 with a .241 on base percentage. So batting lead off, instead of second, has put a serious drag on Campana's batting average and on base percentage.
Castro's the best lead off hitter on this team! The last time Castro was allowed to bat lead off, in 312 at bats, he had a .327 batting average with a .370 on base percentage and a .471 slugging percentage. Imagine, an All Star lead off hitter that gets on base and can slug and steal his way into scoring position. And the Cubs have such an All Star lead off hitter--- and they won't even use him!