What is your c - bet frequency? I think this is a good flop to check behind. 27 / 14 / 4 isn't THAT crazy.
Cbet frequency high, prolly 80% odd. 27/14/4 is over 200k but i guess villain doesnt have that many and its prolly skewed a lot higher for the limited sample he has on me. Interested to know why you check behind on this board? I did want to protect my hand but is there a better alternative?
Well, it's just that I think if we get heaps of money in here the bottom of his range for getting it in is going to be a flushdraw (and often with the A or Q of diamonds which makes it a virtual flip). If you are playing aggressively he is just going to be less likely to make a tough fold of the toppest pair on this board. So, we might think lets protect our hand from draws but, meh - he's not folding any of those draws anyway.
This board is quite bad for him to make a move with complete air if you check - raise him. Just because it is a bad texture for you to make big folds on. So, assuming he is a reg, he will probably have a huge range of hands that he defended preflop with that just check - fold for one bet here. However, if you check behind, you probably can get it in so much better and extract a lot of value on the turn when he decides to check - call one pair or Ace - high hands you beat as bluff catchers.
He'll also lead at a lot of draw completing turns when he doesn't actually have the draw and you can catch a ton of bluffs by just calling a barrell or two in position.
Assuming we are properly rolled I much prefer thinking about things from a perspective of value rather then hand protection. Ya sure, we may see an Ace or a diamond peel on the turn and get some money in bad - but we can also see those cards peel off and catch some bluffed money. Overall, I think there has to be higher EV from getting money in on the turn than the flop.