I think cubs need to call up Vitters at this point. One of Kalish, Ruggiano, and Sweeney could very justifiably be sent down. I'm not sure Vitters is "the answer" but he's hitting .286/.348/.524 with 2 homers in AAA. And honestly at this point hitting above .160 shouldn't be that difficult. I also don't get why they don't go with Lake, Bonifacio, and Schierholtz in the OF with Olt at 3B and Valbuena at 2B. I get wanting to break up a line up with different handed hitters but the cubs bench isn't hitting. I'm also wondering if at this point it would be worth it to call up Chris Coghlan. He's not hitting spectacularly in AAA either but least he's getting on base with a triple slash of .225/.319/.300. He'd give you a left handed bat to replace either Kalish or Sweeney if you sent either down.
What's sad is the "core" players are playing well outside of Castillo. Rizzo is hitting .345/.409/.517. Castro while I wouldn't say is spectacular is hitting .295/.317/.426 which is clearly decent. Shark's got a 1.29 ERA with 7.07 k/9 which is a bit low but his bb/9 is pretty nice at 2.25. Wood is 3.00 ERA 9.50 k/9 and 2.00 bb/9. Bonifacio and Hammel also playing well but the rest of the line up/staff are really letting those players down.
They really need someone to give them a little spark outside those players who are playing well and that likely needs to be a hitter. If they could get something out of Vitters and Olt starts playing a little better I feel like the team would quite a bit more competitive.
