The average stack size in the middle game serves as a benchmark for evaluating a player's standing and strategic options. Staying above it allows for greater flexibility, enabling controlled aggression and deep-stacked maneuvering. Falling below it often necessitates tighter play or well-timed aggression to avoid being pressured by larger stacks. It also influences table dynamics, as shorter stacks may become more risk-averse while bigger stacks can apply leverage.