04-13-06 [poker]Raising preflop is generally more profitable than limping, even with cards that play well multiway and may be a dog to win heads up (like 67s or 22).
Obviously there are a lot of factors involved in this - taking the lead in the hand, building the pot for when you hit, etc. etc. One factor that I don't see mentioned much in general is just the statistical factor of getting in pots with bad players.
Say you have 67s in MP. The table has half good players at about 20% vpip (and tighter to a raise) and half terrible players at 50% vpip (who call raises with junk). If you limp in, it's likely you will play a pot with good players, possible with good players in position on you. If you come in for a raise, it's very likely all the good players will fold behind you, if there are any callers it's far more likely to be the bad players. In a limped pot the chance of an opponent being bad is around 5:2 because of their higher vpip, in a raised pot it's perhaps 4:1 because the good players adjust much tighter to a raise.
Now, regardless of the cards, being in pots with bad players is much more +EV than with good players. This is different than isolating on a bad player, where a bad player enters the pot and then you raise to get heads up with him, I'm talking about when you're opening, or perhaps putting in a button raise after a bunch of limpers - by raising you make it much more likely that you're facing bad opponents.
I'm not talking about the normal reasons to raise or not, cbetting etc. I'm talking about one specific factor which I suspect may be important in why raising certain hands is profitable at SSNL.
For example, if everyone at the table plays the same this factor does not exist; eg. if they're all bad or all good, you may still want to raise certain hands for various reasons, but not for this reason. If the good and bad players at the table don't vary their hands selection based on whether you raise or not this factor doesn't exist.
To be concrete, if a bad player plays 50% of limped pots, and 40% of raised pot, but a good player plays 20% of limped pots and 10% of raised pot, by raising you increase your chance of being against a bad opponent from 5:2 to 4:1.
Also, say there are 4 players behind you. Half are good, half are bad. If you limp, the chance that both good players fold is .8*.8 = 64%, so there's a 36% a good player comes in behind. If you raise, the chance that both good players fold is .9*.9 = 81%, so there's a 19% a good player is in the pot.