Skill-Interactive Earned Run Average (SIERA)
Skill-Interactive Earned Run Average estimates ERA through walk rate, strikeout rate and ground ball rate, eliminating the effects of park, defense and luck. How is it calculated you ask?
SIERA = 6.145 – 16.986*(SO/PA) + 11.434*(BB/PA) – 1.858*((GB-FB-PU)/PA) + 7.653*((SO/PA)^2) +/– 6.664*(((GB-FB-PU)/PA)^2) + 10.130*(SO/PA)*((GB-FB-PU)/PA) – 5.195*(BB/PA)*((GB-FB-PU)/PA)
The statistic is so convoluted that Baseball Prospectus removed SIERA from their toolbox of stats. That’s good enough for me.
...Ideally, what I want from my statistics are black and white outcomes. That’s what I love about OBP – either the player got on base or he didn’t. There’s no sample size error, no assumption of universal causation, no convoluted formula. Putting statistics into a greater context allows us to fully flesh out what a player brings to the table. I recognize that the gripes I present about the stats listed above may be perceived by some as minor. As I said before, I realize that the stats I am uncomfortable with still have value, however, I want accuracy from my stats - not flakiness. It is when these stats are perceived as the be-all and end all that makes me uncomfortable.