Wednesday, July 04, 2007

SNG Strategy - Keeping the Bubble Alive Part #2 - Defence!

In a recent post we had a look at the scenario where a big stack keeps the bubble alive by folding to a micro-stack in order to steal from the mid-sized stacks. An interesting concept which can allow a big stack to accumulate most of the chips for when the bubble bursts. This time we take the perspective of a middle stack in the same situation and ask what can be done to defend against such a strategy. Will use the following stack sizes for the example.

Biggy 8700 ($equity = $41.75)
smally 800 ($equity = $11.24)
Mid #1 - 2000 ($equity = $23.51)
Mid #2 - 2000 ($equity = $23.51)

The blinds are at 400 / 200 and the ante 25, the setup is such that the big stack can lose an all-in to either medium stack without too much damage - and the small stack's blind is 'protected' by having the big stack in the way!

The first example to look at is when mid #1 is in the BB, biggy pushes from the button and smally folds. After posting the blind mid #1 has about $20 in prize pool equity at risk - and winning the hand will push this up to approximately $30. The calling range should be clear here, mid #1 needs at least 66% vs biggy's range. If this range is 'any-2' then that would be around 10% (77+ AJo+), pretty tight...

But this does not really account for the small stack only having 600 chips! Could folding be a better play here to wait for the micro-guy to bust??? In my opinion no, in the example we are using the big-stack is deliberately keeping this player alive... so you may as well take any positive expectation edge offered. Over time this will show a profit - the cost being increased variance (you will bust more but show a bigger profit over a meaningful sample).

But this may not be the only solution.

What about the scenario when mid stack #2 is on the button and the micro-stack is in the small blind? What hands can mid #2 shove?

This is slightly more complex from a mathematical viewpoint - we need to factor in 2 loose calling ranges, one that can bust mid #2 and one that can not. First we put the opponents on ranges.

Suggest that biggy is pretty wide here - something like 75% would not be unusual for a thinking player. Losing the hand will result in having 6700 chips, either smally will overcall - pretty much guaranteeing ITM for the big stack, or he will fold and hope that biggy busts the mid-stack, in which case smally would be posting the SB with only 400 chips in total... on the critical list.

So what about the small stacks calling range. Well if the biggy folds then he really has to call with any-2 cards right - getting 3.5/1 from the pot after all! If biggy calls then smally has a decision to make, the chances of folding into 3rd would be tempting here so we can tighten his range to around 5% (9-9+ AQs+) to account for this.

So, given these ranges what can mid #2 profitably push with??? Well the answer is around 6% - that is 88+ AJs+ AQo+. If we take one step back and ask what mid #1 can push UTG then we need to tighten a little more - something like 4% of hands to account for the extra calling possibility from mid #2.

The last situation to cover is when both the big stack and micro stack fold and the 2 medium stacks are in the blinds. Readers familiar with previous posts should realise that this is a faitly simple scenario - that the BB (mid #2) calling range is narrow enough to make 'any-2' a viable push from mid #1... for more on these kind of decisions check out the 'jump off' pages for various SNG Strategy topics on the left hand side of the blog.

GL at the tables.

Mark

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