Today, our focus is strikeout percentage (K%) and walk percentage (BB%).
There are some great articles on why K% and BB% are better stats to look at for pitchers compared to K/9 IP and BB/9 IP.
Here is a great one from Beyond The Box Score:
The bottom line is, when you use K/9 for pitchers, you become less accurate because of batting average on balls in play and the fact that not all innings are created equally. Best put by Craig Glaser fromHardballTimes.com, “The main difference between the two statistics is that K/9 is based on percentage of outs while K% is based on a percentage of plate appearances.”
If you give up more base runners as a result of a higher BABIP, you become less efficient as a pitcher, limiting your innings. But if you still strike out a lot of hitters, your K/9 number will look deceivingly high. In other words, let’s say one pitcher faces 3 batters in an inning and strikes out all of them and another faces 6 hitters in an inning and strikes out 3. The first pitcher’s strikeout rate (per batter faced) is better than the other pitcher’s, but how that inning applies to K/9, they’re equal. BABIP skews K/9 because if you get more outs on balls in play, it limits your ability to strike out people and if you are not getting those outs, it increases your chances for more Ks.
Another good link on the topic:
For an explanation of K% and BB% for batters, here’s a great link which includes a chart of what is considered good and bad on these lists: