Yes, I hold players like Thornton and Marleau to higher standards. Brown having two superb playoff games is a big win for him.
Moreover, and this is all speculation, when DW said he wants to rewards playoff performance...well, he has to put his money where his mouth is and extend Brown. Perhaps Brown was one of the few players not panicking and falling to pieces during the crash against LA...maybe DW wanted to reward that.
I think that the Sharks tried to reward Sheppard with more ice time and more responsibility, and he grandly squandered it. Moreover, Sheppard had a long history of playing below expectations.
I suspect that if Brown flounders like Sheppard did, he will not be retained next season.