Hey man, thanks for the response! I'm gonna be biased because I have Alex Gordon, and Austin Jackson as my OF on one team... but I think you need to do it. Both players are lead-off hitters. You have Posey so V-Mart would be a player you want to try to trade at some point this season so why not now. Including him in a trade for one starting OF for two starting OF on your roser... yeah. I think some frustration will brew with Austin Jackson at times, but look at the players behind him. Your starting staff is solid so Haren might be something you should deal now since his value is diminishing.
I think it's a fair trade but I'm not sure if this really helps your team. I like Jackson because you might want to boost your SBs. I would look into upgrading a SP with one with more Ks. You also have solid bench players that you could start.