Predictive Starting Pitcher Rankings

In an effort to come up with starting pitcher rankings that have a more predictive than descriptive value, I looked to implement a more meaningful metric in player rater evaluation than ERA—xFIP.

For those of you that don’t know, xFIP is an offspring of FIP—fielding independent pitching—that was developed in the fashion of DIPs theory. I’ll link it’s definition here, and if you don’t know what xFIP is, you can read about it at Fangraphs, because whoever wrote the library entry does a lot better job explaining it than I can.

Like a couple weeks ago when we subtracted wins from player rater value, we will exchange ERA with xFIP from player rankings, and see what players move up and down the most, simple enough.

Rankings With ERA & Rankings With xFIP

The rankings on the left (Z-SCR) represent pitcher rankings with ERA, and the rankings on the right (xZ-SCR) use xFIP to evaluate starting pitchers. Strikeouts, wins, and WHIP (the three other statistics used to measure starting pitcher ability in standard 5×5 roto leagues) are also used in each player’s Z-SCR and xZ-SCR.  (The stats used for this study are current up until last Friday).

What is interesting about these two lists is that 19 out of 20 pitchers are the same in both lists. Bartolo Colon, who is not on the xZ-SCR list, is 17th on the Z-SCR list, and we can all agree that his Fantasy value is largely inflated by unsustainable wins and a favorable strand rate. And while Colon has seen the crux of his Fantasy value rooted in wins, Jeff Samardzija, who is in the xZ-SCR list, but not in the Z-SCR list, has seen his worth wilted away from drought of wins like the Wrigley ivy in the fall.

The players on these lists are the best of the best in 2013, and we should not expect to see more than the minor shifts that are apparent. Now, we will look at a more interesting list that shows which player’s rating changed the most with a substitution of ERA for xFIP.

The players on the left are the pitchers who move up the most in worth when you substitute xFIP for ERA, and the players on the right are the pitchers who lost the most value.

When I look at the players on the left side of the list, I see a group of pitchers who have been filched of appreciation because of their inability to control what is outside of their own ability and fail to amass wins. When I look at the list on the right, I see a group of BABIP mavens whose luck will eventually run out.

The group of players on the left is the group of pitchers that you want to buy low, and the group of pitchers on the right is the group of pitchers you want to sell high.

I’m going to harp on Matt Moore here, and I thought I would just prepare everyone for it.

Moore’s 1.13 ERA in April and 3.30 ERA in May have finally caught up to his 4.10 FIP. Moore’s ERA has regressed to a 3.95 ERA for the season, while his 10 wins have kept his Fantasy value on life support and from completely pushing daisies.  Moore, along with Jeff Locke and Jason Marquis (who are also on the list above, and I don’t think it is a coincidence), is in the top five of walk percentage at 11.9%, which gives me little hope that he, absent his last game, will be able to turn his current streak of misfortune around.

What can we take away?

So now that I am finished deviating off-topic about Moore, let me give my final thoughts on this list.

Player rater value (Z-SCR) is a description of a story that has been told up to a certain point, but stats like xZ-SCR and xFIP are clues for how a particular player’s story will end — foreshadowing, if you will.

For those of you that have seen Requiem for a Dream, let me use a metaphor to drive this point home:

Jared Leto and Marlon Wayans’ lives, in a vacuum, looked to be harmonious in the first 40 minutes of the movie, but anyone could read the tea leaves and tell that the casual heroin use would lead to an end that was bleaker than the way the story began.

Often, the only way to tell how a story will end is to take the time to look at how the story is developing. Just as one could tell how the story would end for Leto and Wayans, astute Fantasy players should be able to tell how the season will end for Marquis and Locke.

Sure, Moore had good results at the beginning of the year, but how did he obtain those results: a low BABIP, lots of walks, and a lot of luck. Let me beg readers to judge players not on their results, but on their process. ERA is the result, and xFIP is the process. Which one do you trust more?

Devon Jordan is obsessed with statistical analysis, non-fiction literature, and electronic music. If you enjoyed him here, reading about these predictive starting pitcher rankings, follow him on Twitter @devinjjordan.