ERAS stands for Earned Run Average, which is a statistic used in baseball to measure the number of runs a pitcher gives up over a nine-inning game. It is calculated by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine. Bullpen stats refer to the statistics of pitchers who are not part of the starting rotation but are used in relief. These stats are important for teams to consider when making decisions about their pitching staff.