You really can not pull well this or that is is the reason. Tough tittys. He had a shot in 2012. He sucked. He went back for a 2nd "full" year at AAA and delt with leg issues. Again tough Tittys. He has not earned a spot so ya he needs to go out and crush the ball and impress or he is a wasted 40 man roster spot. He has been in the system long enough to be judged.
Olt was given the same shot in 2012 and he also sucked. He went back and sucked at AAA. You can blame the tear duct issues but they were supposedly fixed during the season and even after being traded to the cubs he didn't perform well in PCL. But it's ok because he was a formerly highly rated prospect.... ya know like Vitters was?
Again, all i'm saying is if you think Olt can be good, why not Vitters? The last time Olt hit was in 2012 in AA. He hasn't hit AAA pitching and he didn't hit MLB pitching. Vitters has hit AAA pitching an sucked equally bad at MLB but he's also a year younger so he should. Lake can easily be moved to CF where he took half his AB and Sweeney can be a 4th outfield if they so choose. Not to mention the fact that Schierholtz undoubtedly will be traded at some point. And are we really going to worry about playing Sweeney over Vitters? I mean Vitters has potential to be a useful piece going forward if he turns around his career like I'm suggesting. Sweeney is already in his prime and still not that great.
Just to remove some bias here, these are the projections fangraphs have on the two.
Olt
Streamer - 444 PAs 47 runs 14 HRs 47 Rbis 4 SB .217/.302/.379, .8 WAR
Oliver - 600 PAs 67 runs 24 HRs 77 RBIs 2 SB .218/.305/.407, 1.6 WAR
Vitters
Streamer - 21 PAs 2 runs 1 HRs 2 RBIs 0 SB .255/.306/.419, .1 WAR
Oliver - 600 PAs, 69 runs 20 HRs 76 RBIs 6 SB .253/.305/.423, 1.4 WAR
Both projections have vitters with a higher OPS. Obviously streamer has a small sample size but both think he's a higher average guy by a significant margin