I may just be overthinking this a little, and as such, made this more confusing than it should be. Say we're in the middle of the tournament, not in the money just yet, and we are in the BB with a 20BB stack. It folds around to the SB, who has been playing a pretty balanced game, and he shoves for 11BB.

We look down at J9s - now, according to Nash, this is a call, however, is this the overriding factor in our decision here? Do we purely base whether we call or fold on Nash, even though it's the right call, or do other factors come into play that could take precedence?

Obviously, if we were on the money bubble, would this be a straightforward fold based on ICM? What about the tendencies of our opponent - do we simply assume he's shoving based on Nash himself, irrespective of how he's been playing, and make the correct mathematical call, or do we err on the side of caution, and look for a better spot, because let's face it, this is a large % of our stack.

Are there any other considerations? What is your thought process in these spots?

Also - can we loosely adapt Nash when we are in the BB to the BTN or is this explicitly assigned to BB v SB?

Thanks.