Pitching Stats 4: xFIP

xFIP is almost the same thing as FIP, just with something ‘xtra’.  The idea is that while pitchers are responsible for the 3 True Outcomes (HR, BB/HP, and K), home runs can also be subject to luck.  For example, a fence-scraper over the short right porch in Fenway might not be a home run through the marine layer at Dodger Stadium.  What does this tell us about the pitcher’s expected performance?

Well, to account for the vagaries of chance, xFIP takes all of a pitchers fly balls and multiplies them by the league average HR/FB rate.  Basically, it assumes a number of HR a pitcher would have given up based on the number of fly balls their opponents hit rather than the number of HR they actually did give up.

It feels like splitting hairs to me, but hey.  That’s baseball.  The formula for xFIP is just like FIP with that one change:
xFIP = ((13*(Fly balls * lgHR/FB%))+(3*(BB+HBP))-(2*K))/IP + constant

The constant is the same FIPConstant we calculated for FIP.  So, this one is pretty straight-forward, except that we need the HR/FB% for the league.  We’ll go back to our FIPConstant table and add it there for each league year.  Our FIPConstant table now looks like this:

DROP TABLE IF EXISTS FIPConstant;
CREATE TABLE IF NOT EXISTS FIPConstant AS

SELECT
      year
    , league_id
    , hra_totals/fb_totals AS hr_fb_pct
    , @HRAdj := 13*hra_totals AS Adjusted_HR
    , @BBAdj := 3*bb_totals AS Adjusted_BB
    , @HPAdj := 3*hp_totals AS Adjusted_HP
    , @KAdj  := 2*k_totals AS Adjusted_K
    , @InnPitch := ((ip_totals*3)+ipf_totals)/3 AS InnPitch
    , @lgERA := round((er_totals/@InnPitch)*9,2) AS lgERA
    , round(@lgERA - ((@HRAdj+@BBAdj+@HPAdj-@KAdj)/@InnPitch),2) AS FIPConstant
FROM (
         SELECT year
                , league_id
                , sum(hra) as hra_totals
                , sum(bb) as bb_totals
                , sum(hp) as hp_totals
                , sum(k) as k_totals
                , sum(er) as er_totals
                , sum(ip) as ip_totals
                , sum(ipf) as ipf_totals
                , sum(fb) as fb_totals
          FROM players_career_pitching_stats
          GROUP BY year, league_id
      ) AS x;

I added the formula above to the CalcPitching table and we’re done.  OOTP doesn’t track xFIP (at least in v18), so there’s nothing to compare it to.  This one’s done.

DROP TABLE IF EXISTS CalcPitching;
CREATE TABLE IF NOT EXISTS CalcPitching AS

SELECT
    i.player_id
    , i.year
    , i.stint
    , i.team_id
    , i.league_id
    , split_id
    , i.ip
    , i.ab
    , i.tb
    , i.ha
    , i.k
    , i.bf
    , i.rs
    , i.bb
    , i.r
    , i.er
    , i.gb
    , i.fb
    , i.pi
    , i.ipf
    , i.g
    , i.gs
    , i.w
    , i.l
    , i.s
    , i.sa
    , i.da
    , i.sh
    , i.sf
    , i.ta
    , i.hra
    , i.bk
    , i.ci
    , i.iw
    , i.wp
    , i.hp
    , i.gf
    , i.dp
    , i.qs
    , i.svo
    , i.bs
    , i.ra
    , i.cg
    , i.sho
    , i.sb
    , i.cs
    , i.hld
    , i.ir
    , i.irs
    , i.wpa
    , i.li
    , i.outs
    , i.war
    , @InnPitch := ((3*ip)+ipf)/3 AS InnPitch
    , round((9*i.k)/@InnPitch,1) AS 'k9'
    , round((9*i.bb)/@InnPitch,1) AS 'bb9'
    , round((9*i.hra)/@InnPitch,1) AS 'HR9'
    , round((i.bb+i.ha)/@InnPitch,2) AS WHIP
    , round(i.k/i.bb,2) AS 'K/BB'
    , i.gb/i.fb AS 'gb/fb'
    , round((i.ha-i.hra)/(i.ab-i.k-i.hra-i.sh+i.sf),3) AS BABIP
    , round((i.er/@InnPitch)*9,2) AS ERA
    , round(((13*i.hra)+(3*(i.bb+i.hp))-(2*i.k))/@InnPitch+f.FIPConstant,2) AS FIP 
    , round(((13*(i.fb*f.hr_fb_pct))+(3*(i.bb+i.hp))-(2*i.k))/@InnPitch+f.FIPConstant,2) AS xFIP
    
    
FROM players_career_pitching_stats AS i
    INNER JOIN FIPConstant AS f ON i.year=f.year AND i.league_id=f.league_id
WHERE i.split_id=1 AND i.league_id<>0;