The two had been chirping at each other in recent practices and walkthroughs, per beat reporters on the scene. Apparently, Zimmer had had enough.
"They did not make me happy," Zimmer said, of both players not practicing, via the Pioneer Press. "It's not injury related."
The head coach didn't elaborate on holding out two of his key players from practice other than to say the issue was "just undisciplined stuff."
It's not unusual for a coach of Zimmer's ilk to make an example out of his star players, particularly deep into training camp when concentration levels can begin to wane.
"It's that time of training camp to go play against somebody else," offensive coordinator John DeFilippo said. "It's getting a little chippy out there, so it's time to take some chippiness out on somebody else."