With the 2013 season well under way, both baseball teams in the Bay Area have gotten off to hot starts. While the A’s record can be attributed to a hot offense, neither team has played many good teams and this is reflected in their respective records. As the season opened, expectations were high for both team’s starting rotations. With 2 weeks in the book, let’s compare each team’s starting 5.
The first metric we will use to compare starting rotations is Jeff Sagarin’s MLB ratings which include the value of predicted ERA. Predicted ERA is “..what the pitcher’s ERA “should be” (NPERA) given his raw statistics NORMALIZED to composite major league play of 1946-1999″. This means that “…if the pitchers are NORMALIZED, that means that their predicted ERA’s are what they would have achieved if they had pitched in the hypothetical composite major leagues of 1946-1999.”. An average pitcher would have an ERA of 3.87. Lets take a look at each team’s predicted ERAs.
Griffin, A.J. 2.55
Milone, Tommy 3.48
Colon, Bartolo 3.91
Anderson, Brett 4.04
Parker, Jarrod 12.10
Bumgarner, Madison 2.45
Cain, Matt 4.08
Lincecum, Tim 4.51
Zito, Barry 4.73
Vogelsong, Ryan 5.13
As we can see, from the top down the Giants have the better stating rotation, mainly due to Jarrod Parker’s horrible starts. We can also attribute part of the difference in ERA to the league each team is playing in (this article goes into detail about the differences, citing a value of 0.41 ERA lower for pitchers in the NL). If we drop the worst two pitchers, the A’s rotation has a slight advantage at 3.45 to 3.94.
The next metric used to compare each rotation is WAR, specifically Fangraph’s WAR. WAR (Wins Above Replacement) was developed for comparing players across varying categories, taking into account park factors and league factors to compare players across leagues, divisions and teams.
Griffin, A.J. 0.4 Milone, Tommy 0.3 Colon, Bartolo 0.2 Anderson, Brett 0.0 Parker, Jarrod -0.3
Bumgarner, Madison 0.2 Cain, Matt 0.2 Lincecum, Tim -0.2 Zito, Barry 0.1 Vogelsong, Ryan 0.3
As we can see, both teams rotations are even on the WAR scale. Interesting to note how little stock WAR puts in ERA (WAR uses Fielding Independent pitching, FIP) rating Ryan Vogelsong as the Giants best pitcher.
In conclusion, the starting rotations for both the A’s and the Giants are about evenly matched. Taking into consideration Jarrod Parker’s poor outings, I will the give the edge to the Giants at this particular moment. It will be interesting to see how these rotations stack up as the season progresses.