In my previous post, I discussed the pros and cons of two commonly used Wins Above Replacement statistics for pitchers:
The fWAR statistic is based on FIP and innings pitched. As such, it favors pitchers with a high number of innings pitched and strong peripherals – high strikeout rates and low walk and home run rates. It is forgiving to pitchers with high ERAs relative to their peripherals. Table 1 shows the American League WAR leaders in 2010. Those who favor this FIP based WAR are probably choosing between Francisco Liriano (6.1 fWAR), Cliff Lee ( 6.0) and Felix Hernandez (5.9) in a close Cy Young race.
The rWAR statistic is based on innings pitched and runs allowed with adjustments made for team defense (as measured by Total Zone) behind a pitcher. It is friendly to a pitcher with a high number of innings and a low RA - which is the same as ERA except it considers all runs rather than just earned runs. A pitcher with a low RA, despite weak defensive support, will do particularly well on this statistic. Rally’s WAR is unaffected by peripherals. As seen in Table 2, supporters of rWAR likely see Hernandez as the clear Cy Young favorite.
Fans who don’t want to choose between runs allowed and peripherals ( I fall in this category) might prefer a combined WAR. One way to do this is to compute a simple average of fWAR and rWAR as displayed in Table 3. Using this approach, Hernandez (5.8 Avg WAR) looks like the top pitcher, followed by Liriano (5.4), Weaver (5.1) and Lee (4.8).
Another thing you may notice is that some pitchers do much better on one stat than the other. For example, Liriano (6.1 fWAR versus 4.7 rWAR) and Lee (6.0 vs. 3.5) do far better on fWAR because of their strong peripherals and good but not great RAs. On the other hand, hurlers such as David Price (3.7 vs. 4.6) and Carl Pavano (3.6 vs. 4.6) do better on rWAR.
Table 3: AL Average WAR Leaders