It was hitting coach Kevin Long, and he rather stupidly mentioned Cano's propensity to jog to first base on obvious outs (mentioned by a few Sox fans here).
"If somebody told me I was a dog, I'd have to fix that. When you choose not to, you leave yourself open to taking heat, and that's your fault. For whatever reason, Robbie chose not to," Long said.
It was obviously something that bugged Long and now that he doesn't have to deal with it, he blurted it out. He was quickly rapped on the knuckles by the team.