I think I saw 7% open-raise or raise. If that's so, I wouldn't bet too much that he plays like a rock post-flop. Anyway, if I am going to check-raise that flop against a rock with my bad luck against the rocks when doing so (even with a flush draw possible flop, I might not check-raise with my luck nor vs. tight 3bettors as I would need maybe a minimum of 50-50 being ahead ALL the way to make that check-raise. Welcome to the world of being out of position against a rock), I am going to call it down here until it comes with an ace or two picture cards, especially K and Q, as with a low flop and tilting rock (that he might very well be and I would be counting on that if I am cr that flop, and if I am not, I am just calling twice - I figure he bets the turn with this flop - and think what I will do at the river). But vs. a normal rock, what others are saying is true and the reason why one makes money against the rocks (they don't get full value from their hands because they don't play the more marginal hands nor make moves and bets with the more marginal and semi-hands often enough).