Performance Analysis: It just goes to show how amazing Mariano Rivera's career has been when he can post an ERA of 3.20 and those of us in the analysis community all can think something must be wrong. That is the scenario we are presented with, though. Despite striking out batters at his highest rate since 1996 (his first season as a full-time reliever) and handing out free passes less often than ever, Rivera is struggling, relative to expectations.
The number that immediately jumps out this season is his home run rate, which sits at 1.8 HR per nine innings. You may think this is easily explained by his new digs. The new Yankee Stadium hasn't exactly been friendly to pitchers these past two months, but that's not the case: Mo has allowed three homers at home in 16 2/3 innings, and a pair on the road in about half as much work. Four of his five homers allowed have come on fly balls -- the other was a liner -- though he isn't giving up more flies than he usually does.