Whenever I’m asked “how many games do you think (insert pitcher here) will win?” I have to bite my tongue. How the hell am I supposed to know? I can tell you what I think his ERA will be, or his K/BB ratio, but I have no idea how the other 24 guys are going to perform during his starts.
Last year, Brandon Webb was 10th in ERA but first in wins. Am I supposed to believe he should have won the Cy Young because of the win total? Did he somehow magically improve the other guys on the team by just stepping on the mound? Maybe his girlfriend promises to bake the team cookies if the team gets Brandon a win? Why didn’t Anna Benson think of bribing Kris‘ teammates? Kris could have been a 20-game winner!
WHIP, DIP percentage, K/BB ratio, and to a slightly lesser extent ERA, are all more useful to me when evaluating a starting pitcher. Any time you have to factor run support and bullpen into evaluating a starting pitcher, it's bad news.
When measuring a player, it is important to eliminate as little variables as possible. Aside from errors, all of these stats are too dependent on a player’s teammates. Errors are very circumstantial as well. In our most numerical game, it is important that we know which numbers are and are not meaningful. I hope to see these four statistics be de-emphasized.