In this hand there are three players to the flop. The flop is 9♥ J♥ T♦ and the player in position hits a set and raises the middle player. The commentator has this to say about the raise:
I like this raise, the board is sopping wet, he's going to want to try to protect his set.
My understanding of "protecting" your hand is that you want to bet out when you have a made hand in such a way that prices out draws. But in this hand, as the commentator says, the board is "sopping wet" so there are a lot of other made hands out there which could already beat a set including any 89, 8Q, and KQ. Given the action pre-flop any of these hands could be in play.
So given this, how is raising "protecting" anything? Is the raiser assuming the initial bettor doesn't have any of these hands that could beat him and is just on a draw? Is it more an attempt to get more information than actually protecting anything? In the hand in question, UTG then re-raises and gets called (all-in for less if I'm not mistaken), and the player with a set still appears to have a difficult decision before laying down the hand. Is it really so unlikely that either player has him beat giving the preceding action? (The odds are showing the player with the set actually has a 57% chance of winning, although without knowing the other player's cards it seems harder to know).
This question talks about betting with a set on the flop but I'm not so much interested in betting versus not betting, but more about whether or not this particular type of bet, especially in position, is really protecting and why, and how one can identify when it is appropriate to try it when there is a decent chance they are already behind.