SIERA is one of the best saber tools for measuring the true effectiveness of a pitcher. The pitchers with the lowest SIERA tend to be the most valuable in Fantasy. Here is the explanation of SIERA and why you should incorporate it into your Fantasy toolbox for evaluating pitchers. Big thanks to the guys at Fan Graphs for the following info. Lastly, a list the top SIERA pitchers in the Majors.
SIERA attempts to answer the question: what is the underlying skill level of this pitcher? How well did they actually pitch over the past year? Should their ERA have been higher, lower, or was it about right?
But while FIP and xFIP largely ignore balls in play — they focus on strikeouts, walks, and homeruns instead — SIERA adds in complexity in an attempt to more accurately model what makes a pitcher successful. SIERA doesn’t ignore balls in play, but attempts to explain why certain pitchers are more successful at limiting hits and preventing runs. This is the strength of SIERA; while it is only slightly more predictive than xFIP, SIERA tells us more about the how and why of pitching.
Here’s what SIERA tells us:
Strikeouts are good…even better than FIP suggests. High strikeout pitchers generate weaker contact, which means they allow fewer hits (AKA have lower BABIPs) and have lower homerun rates. The same can be said of relievers, as they enter the game for a short period of time and pitch with more intensity.
Also, high strikeout pitchers can increase their groundball rate in double play situations. Situational pitching is a skill for pitchers with dominant stuff.
Walks are bad…but not that bad if you don’t allow many of them. Walks don’t hurt low-walk pitcher nearly as much as they hurt other pitchers, since low-walk pitchers can limit further base runners. Similarly, if a pitcher allows a large amount of base runners, they are more likely to allow a high percentage of those base runners to score.
Balls in play are complicated. In general, groundballs go for hits more often than fly balls (although they don’t result in extra base hits as often). But the higher a pitcher’s groundball rate, the easier it is for their defense to turn those ground balls into outs. In other words, a pitcher with a 55% groundball rate will have a lower BABIP on grounders than a pitcher with a 45% groundball rate. And if a pitcher walks a large number of batters and also has a high groundball rate, their double-play rate will be higher as well.