Ah, the power of the Internet. I received a handful of email responses and one anonymous comment about a recent blog post in which I claimed a big blind should essentially defend with 100% of their range when facing a 3x small blind open (click here to read that original post).
Turns out I was wrong in that post. Let me explain... or, better, I'll let the anonymous commenter explain:
"Your goal is not to be profitable with your whole range, your goal is to be as profitable as possible. This means calling only with hands that individually have enough equity. So you should fold hands like 74o which only has 32.35% equity."
He (or she) (and all the emailers, too) correctly pointed out that running a hero range against villain's range is silly. What actually matters are individual specific hands played against villain's range; i.e., I'm not playing a range of hands from the big blind, I'm playing a single specific hand. In other words, each single hand has to have at least 33% pot equity by itself against the villain's range to make calling a break even play with that hand.
So, that's exactly what I did-- I ran my equity calculator a whole slew of times with individual hands against the villain's range. I kept track of which hands had greater than 33% equity, and then plotted them on a card matrix. Here's my new, corrected defending range from the big blind:
Again, don't take the wrong message from this. For example, I'm pretty sure I wouldn't actually always defend with Q5o or K3o when facing a SB open; these kinds of hands have only slightly higher than 33% equity, and are generally quite difficult to play postflop; they could end up actually costing you money in the long run unless you play them perfectly. In other words, it's a pretty close decision with a lot of the hands that the matrix indicates are playable...
....but the bottom line message is still clear: the range of hands that you can/should defend with is pretty damn wide.
Thanks to all you who sent me comments. I really appreciate all y'all settin' me straight.
All-in for now...