Stats: Strikeout rate (K%), walk rate (BB%) and HR/FB (home run per fly ball rate)
Where can I find them: FanGraphs and Baseball-Reference should carry all, or at least most, of these.
What do they do: These stats are fairly self explanatory. They tell you how many batters a pitcher has walked or struck out by plate appearance. Home run per fly ball rate tells you how often a pitcher gives up a home run when they allow a fly ball.
How can I use it: Want an easy way to determine whether a pitcher is striking out more hitters? There you go. These rates can also give you an idea of whether a player is performing better or worse over their career in these categories. That could help Fantasy owners identify breakouts sooner than normal. HR/FB rate is a good way to figure out whether a player is allowing more home runs than usual, or whether they've kept the ball in the ballpark at a suspiciously low rate. Once you get a feel for these stats, you can look primarily at these three things in order to determine whether a player might be in for better, or worse, numbers moving forward. Hate FIP and xFIP? This is a way around that.
Example: Last season, Patrick Corbin saw a slight jump in his strikeout rate, which may have contributed to his breakout. A.J. Burnett was able to turn things around in Pittsburgh due to a lower walk rate. After years of a fairly low home run rate, Matt Cain saw his numbers jump last year, which led to his disappointing season. In most cases, you'll want to compare rates to a player's career norms. While not perfect, it can sometimes tell you what players have improved or declined.
What are the problems with these stats: No surprise here, but small sample issues exist. Cain will likely post a better HR/FB rate this season, but he's had bad luck early. Pitching in Colorado for one of his few starts will do that. On top of that, context is generally required when you find a player who is showing better or worse career numbers in these categories. Corbin's strikeout rate jumped because he was throwing harder. Burnett's walk rate dropped because he used a new pitch selection and started working with a catcher who could frame better. Don't just assume players suddenly get better or worse, do some digging and see what you can find to support, or refute your initial thought.
Anything else: Look up some pitchers you are familiar with in order to get a better sense of what having a 20 percent strikeout rate means. Continue to do this until you get an idea of what is acceptable for strikeout and walk rates. This will help you determine whether a pitcher is showing the skills needed to succeed. If a player is posting a terrible ERA, but is still showing similar strikeout and walk skills, it's reasonable to think they can rebound.
Next post: It might be time to move to hitting. I'll make sure there's not anything else I want to cover on the pitching side, and we'll start our transition.