Last year, the 102-win Cleveland Indians were one of the great teams of the modern era: Their starting pitchers had the American League's lowest ERA, their offense scored more runs per game than all but two AL teams, and their defense was, by Defensive Runs Saved, the AL's third best.
And their bullpen! Collectively, Cleveland's relievers had the game's lowest ERA. Their sOPS+ -- OPS allowed, relative to the rest of the league's relievers -- was baseball's 19th best since 1988, when the current era of bullpen usage more or less began.