Good question.
Difficult to answer in a vacuum without some more information on the other players. In particular, how often is the BB squeezing here and what range do you think he’s squeezing with? Are these guys likely to stack off with an overpair or TPTK type hand?
Be good if someone better at maths could confirm my numbers below. These are obviously basic numbers in any event and assume you win the pot when you hit and lose when you miss. Maybe one of the coaches can help with more complex analysis.
Scenario 1 –BB squeezes to 12bb, MP folds
Here you have to call 9bb to play IP in a three bet pot of 25.5bb.
The odds of flopping a set (or better) is 11.8% or roughly 1 in 8.5 (7.5:1 as a ratio).
In order to make this a breakeven call you need to win a total of 76.5bbs (8.5 x 9bb) when you hit your set (assuming you never win the pot when you miss). So you need to win, on average, an extra 51bb (76.5bbs less the 25.5bbs already in the pot) every time you hit.
So basically, the narrower the squeezing range/more likely he is to stack off with worse the more often you can call here as you will be more likely to win your 51bbs. Reads are clearly the key here.
For example If Villain is squeezing 5% (99+, AQo, AQs, KQs), the call starts to look marginal as you are less likely to stack him unless he’s a maniac. He’s probably not going to go crazy with TT on an A6Q board for example.
This spot is pretty dynamic and read dependant.
Scenario 2 –BB squeezes to 12bb, MP calls
Here, because of the extra money in the pot from MP you only need to win on average an extra 39bb (76.5bbs less the 37.5bbs already in the pot) every time you hit and there are two players who could pay you off.
By default, I think you can call here.
Scenario 3 – BB squeezes to 15bb, MP folds
Here you need to win a total of 102bb when you hit (8.5 x 15bb). This equates to 68.5bb (102bb less 33.5bb already in the pot) more that you need to average when you hit.
This is starting to get tougher and you can only really call against a narrow squeeze range and/or against spewy players or calling stations.
By default, I think this is a fold without a specific reason to call.
Scenario 3 – BB squeezes to 15bb, MP calls
Because of the extra money in the pot you need to win 53.5bb in this scenario.
This is closer and your reads will obviously factor but by default, I think this is a call.