From Team Fortress Wiki
Team Balance is a gameplay feature that automatically balances teams that have been made uneven (for example, by a number of players disconnecting on one side) by switching one or more players at random from the side with the most players. When team balance is initiated, a timer appears informing the players how much time is left until the switch is made.
Though the balancing process is a necessary one, many players have voiced disapproval at being switched to the losing side shortly before the end of a match, or while playing on a team comprised of people with whom he is in charge of or engages in regular communication with. In such a situation, the switched player may choose to attempt to arrange a manual switch with a member of the opposing team.
It is generally frowned upon to switch back to your original team after being autobalanced (such as moving to spectate and allowing another person to be balanced, and reclaiming their spot on the original team).
- Improved autobalance calculation code when determining who to switch
- Changed team autobalance code to not balance the teams when the active round timer shows less than 60 seconds