Ive been looking at SIMs in holdem resources for all in calling ranges at final tables. I find the ranges exceptionally tight even for under 5 bb when the next smallest stack is 10bb. For example, we have 5bb in the bb and utg +1 shoves for 15bb, all fold to us in the BB, HRC is telling me i should have a 6% all in calling range. This cant be correct.
Can anyone point me to some resources to better understand what the calculator is doing for these spots ?