For what it's worth, Pens radio guy, Steirgerwald basically backed this up.
The day after the Pens were eliminated he did an interview on XM and the guy asked what injury Kessel had to explain his play. Steigy responded that Kessel wasn't injured but he was sort of pouting because he did not like who he was beig asked to play with night in and night out. The person questioning him even asked him to clarify and he repeated what he said. Sullivan not playing him with Malkin apparently pissed him off.
The day after the Pens were eliminated he did an interview on XM and the guy asked what injury Kessel had to explain his play. Steigy responded that Kessel wasn't injured but he was sort of pouting because he did not like who he was beig asked to play with night in and night out. The person questioning him even asked him to clarify and he repeated what he said. Sullivan not playing him with Malkin apparently pissed him off.