Kuntz said he talked with Chiefs staffers over it all ... and while he regretted tweeting about it and apologized to Mathieu over it -- he stood by his claims.
"I am standing by what I heard, but I should not have tweeted it, in hindsight," Kuntz said. "It was a frustrating game but should not have shared that info on social. For this, I apologize."
Mathieu recorded 6 tackles in the game ... but it wasn't close to enough to help K.C. lock down a win -- and the Chiefs are now just 3-4 in the season despite heading into the year with Super Bowl hopes.