Castro entered Monday's game against the Pirates batting .241, well below the .297 average he compiled in his first three seasons. Barney was batting .209, while Rizzo was hitting .231, but led the team with 22 home runs and 77 RBIs.
Sveum will meet with each player one on one for the end of the season wrapup, although it has yet to be determined if they'll do those sessions during the final homestand, which ends Wednesday, or this weekend in St. Louis.
Sveum did see positive signs with the bullpen heading into 2014 with the performances of pitchers such as Hector Rondon, Justin Grimm, Pedro Strop and Carlos Villanueva.
"We obviously have some pieces we have control over," Sveum said. "The bullpen going into next year will be a lot more solidified than it has the last two years."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.