"[Replay] is kind of an organic, work in progress for everybody, getting a feel for its usage," Renteria said.
Does the Cubs' rookie manager like it?
"I think if it helps us clean up some plays, I think it's helpful," Renteria said. "I still think the umpires do a great job. They have a tough job to do and they don't want to screw it up, they want to get the calls right. We're emotionally vested in everything, and they're emotionally vested in doing a good job. We both have to grow a little thicker skin in dealing with each other the best way we possibly can."
It seems managers are walking deliberately from the dugout to talk to an umpire about a play, which gives the coaches and others in the clubhouse time to review the video before deciding whether to challenge a call or not.
"I think everybody's doing that," Renteria said. "I'm assuming they appreciate us doing that also, because they know it's getting reviewed. If there is a bad call or a close call, if it gets overturned, it gets overturned. They're allowing us to be able to do that.
"I think [the umpires] want to get the calls right," he said. "They've probably been living a pretty tough life with all the cameras around [and second-guessing]. They're human beings and they don't want to do things that affect the game. Maybe they're thankful about it."
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.