Revisiting Rotation Spots

Earlier this offseason I had a few posts talking about the average ERA and FIP for each rotation spot in 2007. Now, one season isn't a whole lot of context in baseball: depending on what you're looking at, there can be a lot of fluctuation from year to year. That's why I thought it would be interesting to look at FIP and ERA by rotation spot over the past five seasons.

The methodology is the same as in the previous posts. A team's starts are broken up into quintiles, based on the FIP or ERA of their pitchers, and a weighted average is taken in each quintile based on the starts and FIP of each pitcher in it. For example, a team with a normal 162-game schedule would have their rotation spots looking like: #1 - 33 starts, #2 - 33 starts, #3 - 32 starts, #4 - 32 starts, #5 - 32 starts. If Pitcher A made 20 starts with a 3.30 ERA and Pitcher B made 15 starts with a 3.40 ERA and everyone else on the staff had higher numbers, Pitcher A's 20 starts would be combined with 13 of Pitcher B's starts to yield an average ERA of 3.34 in the top 33 starts. The remaining two starts from Pitcher B would be combined with Pitchers C, D, etc., to figure out the average ERA of the other rotation spots.

The numbers below in the tables are found by combining all the starts in the league for each season (~2490 for the NL and ~2268 for the AL), separating them into fifths, and using the process described above. The "Average" row is the average of the five numbers above. Also remember that rather than adjusting the constant added to the FIP number every season like The Hardball Times does, I just use 3.2 across the board.

NL Rotations by FIP, 2003-2007

Year	FIP	#1	#2	#3	#4	#5
2003	4.55	3.42	4.13	4.52	4.95	6.15
2004	4.61	3.37	4.14	4.63	5.09	6.47
2005	4.45	3.35	4.05	4.43	4.95	5.85
2006	4.66	3.62	4.21	4.63	5.07	6.25
2007	4.60	3.48	4.17	4.66	5.04	6.04
Average	4.57	3.45	4.14	4.57	5.02	6.15

NL Rotations by ERA, 2003-2007

Year	ERA	#1	#2	#3	#4	#5
2003	4.40	2.97	3.81	4.24	4.92	7.04
2004	4.43	3.00	3.75	4.22	4.87	7.55
2005	4.23	2.81	3.70	4.23	4.70	6.23
2006	4.65	3.25	4.00	4.57	5.12	7.07
2007	4.64	3.29	3.97	4.50	5.12	7.03
Average	4.47	3.07	3.85	4.35	4.95	6.98

Note: NL defenses must have taken some sort of hit in the past two seasons to have ERA's jump the way they did without FIP being similarly affected. 2005 is a kind of fluky season, but the FIP from before then are similar to 2006-2007 and yet ERAs are lower. Maybe it's an injury issue, as well.

AL Rotations by FIP, 2003-2007

Year	FIP	#1	#2	#3	#4	#5
2003	4.73	3.57	4.30	4.78	5.17	6.30
2004	4.80	3.75	4.40	4.77	5.19	6.27
2005	4.56	3.65	4.18	4.56	4.92	5.77
2006	4.66	3.55	4.18	4.63	5.08	6.31
2007	4.47	3.47	4.01	4.45	4.88	6.02
Average	4.64	3.60	4.21	4.64	5.05	6.13

AL Rotations by ERA, 2003-2007

Year	ERA	#1	#2	#3	#4	#5
2003	4.66	3.18	4.05	4.56	5.37	6.97
2004	4.83	3.57	4.35	4.84	5.22	6.93
2005	4.52	3.21	3.85	4.40	5.07	6.73
2006	4.73	3.36	4.17	4.62	5.10	7.06
2007	4.61	3.29	3.88	4.42	5.23	7.00
Average	4.67	3.32	4.06	4.56	5.20	6.93

Now for the fun part: finding an average team rotation (using ERA) over the last five seasons. Players included must have started 60% of their games and had 500+ innings pitched in their league over the last five seasons.

First, the National League:

1. Average #1, 3.31 ERA: Carlos Zambrano (3.30 ERA)
2. Average #2, 3.91 ERA: Tom Glavine (3.97 ERA)
3. Average #3, 4.40 ERA: Chris Capuano (4.39 ERA)
4. Average #4, 4.96 ERA: Claudio Vargas (4.96 ERA)
5. Average #5, 6.68 ERA: Eric Milton (5.54 ERA) - he was the worst qualifier under my criteria. You'd have to go down to a 100 IP minimum to find guys who actually put up a 6.68 ERA in the NL, which tells you how often guys are shuffled in and out of the #5 spot due to injuries.

Second, the American League:

1. Average #1, 3.57 ERA: C.C. Sabathia (3.61 ERA)
2. Average #2, 4.19 ERA: Kenny Rogers (4.18 ERA)
3. Average #3, 4.61 ERA: Jose Contreras (4.57 ERA)
4. Average #4, 5.13 ERA: Joel Piniero (5.05 ERA)
5. Average #5, 6.66 ERA: Sidney Ponson (5.37 ERA) is the worst qualifier. You again have to go down to a minimum of 100 IP to find guys at 6.66 or worse.