Thursday, September 09, 2010

Hernandez Versus Sabathia

Last year, the voters for the Cy Young award selected 16-game winner Zach Greinke over 19-game winners Felix Hernandez, CC Sabathia and Justin Verlander.  Based on ERA and sabermetric statistics such as Wins Above Replacement (WAR), they clearly made the right choice.  In the the National League, they selected 15-game-winner Tim Lincecum instead of 19-game winner Adam Wainwright.  There would have been no shame in giving the award to Wainwright, but again I think the made the correct selection.  Those were two of the three lowest win totals for starting pitchers in the history of the award (Brandon Webb also won 16 games in 2006).  

Traditionally, the writers who vote for the award have made games won a major criteria.   In 1990, for example Clemens had 21 wins and led the American League with a 1.93 ERA, but lost out to 27-game winner Bob Welch, who had an ERA a full run higher (2.95).  That appears to be changing as they seem to be recognizing more than ever that wins is not the fairest way to evaluate pitchers.  This year will be particularly interesting though as they may have to choose between a potential 20-game winner and pitcher with fewer than 15 wins.

As it stands now, Yankees left-hander CC Sabathia has a 19-6 record. Felix Hernandez of the Mariners stands at 11-10.  Readers of this blog don’t need me to explain the failings of won-loss record for pitchers, but this case is so extreme it’s worth mentioning the run support argument.  While Sabathia has benefitted from 6.07 runs per game, King Felix has only received 3.16 runs per game.  That’s almost three more runs per game for Sabathia!  That’s hardly a fair comparison

Sometimes, pitchers accumulate a lot of wins because they are workhorses which pitch deep into games.  One might guess that a 19-game winner would be pitching deeper into games than an 11-game winner, but, in this case, Hernandez actually has more innings pitched (219 1/3 versus 209).  So, the wins statistic is not going to work here at all. 

Since the main job of a pitcher is to give up as few runs as possible, a good starting point in pitcher evaluation is ERA.  Table 1 shows that Hernandez leads Sabathia in ERA by a wide margin (2.30 versus 3.14).  The ERA leader is Clay Buchholz of the Red Sox at 2.25.  However, Buchholz has pitched only 151 2/3 innings, so he has not helped his team as much as Hernandez.  

Table 1: AL ERA Leaders

Pitcher IP ERA
Buchholz, Bos 151 2/3 2.25
Hernandez, Sea 219 1/3 2.30
Cahill, Oak 165 2/3 2.72
Price, TB 178 2/3 2.87
Wilson, Tex 177 3.10
Weaver, LA 189 3.14
Sabathia, NY 209 3.14

In order to give pitchers credit for quantity of innings pitched as well as quality, Pete Palmer introduced the Pitching Runs statistic in 1984.  Pitching Runs tells us the number of runs saved by a pitcher compared to league average.  In it’s purest form, it is based on a pitcher’s IP and earned runs (ER) and the league ERA (Lg ERA):

Pitching Runs = IP x Lg ERA/9 – ER.

The Baseball-Reference version also adjusts for ballpark.  Hernandez has 39 Pitching Runs (See Table 2) which means that he has saved his team 39 runs compared to what the average pitcher would have saved in his place.  Because his greater workload is taken into account,  Hernandez leads Buchholz by 7.7 runs.  Sabathia is only 10th in the league with 19.5. 

Table 2: AL Pitching Runs Leaders

Pitcher IP Pitching Runs
Hernandez, Sea 219 1/3 39.0
Buchholz, Bos 151 31.3
Price, TB 178 2/3 24.6
Cahill, Oak 165 2/3 23.9
Wilson, Tex 177 22.2
Weaver, LA 189 21.3
Lester, Bos 182 20.9
Liriano, Min 172 1/3 19.9
Gonzalez, Oak 179 2/3 19.7
Sabathia, NY 209 19.5

A shortcoming of both ERA and Pitching Runs is that the don’t consider defensive support behind a pitcher.  The WAR statistic developed by Sean Smith and listed at Baseball-Reference attempts to take fielding into account.  WAR is calculated as follows:

  1. Determine how many runs a pitcher allowed.

  2. Calculate average runs allowed by pitchers facing the same teams for the same number of innings as the pitcher of interest.

  3. Adjust for team defensive runs saved based on Total Zone.  Total Zone is computed from plays made, errors, which fielders fielded each out and hit, batted ball type, handedness of pitcher and batter, and park adjustments.

  4. Multiply by 1.22 to get replacement level for an AL starter.

  5. Subtract (4) from (2) to get WAR. 
Table 3 shows that Felix Hernandez was the clear leader in WAR with 5.7.   This says that Hernandez contributed close to six wins more than you would expect from a replacement level player.  Sabathia is 10th in the league with 4 WAR. 

Table 3: AL Starting Pitcher WAR Leaders

Pitcher WAR
Hernandez, Sea 5.7
Weaver, LA 4.8
Buchholz, Bos 4.8
Liriano, Min 4.7
Wilson, Tex 4.6
Price, TB 4.6
Pavano, Min 4.4
Lester, Bos 4.3
Danks, Chi 4.2
Sabathia, NY 4.0

Based on ERA, Pitching Runs and WAR and every other statistic other than wins, Hernandez appears to be the superior pitcher to Sabathia this year.  It will be very interesting to see how the vote turns out if Sabathia wins 20+ and Hernandez wins only 11 to 13 games.

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