Tuesday, October 16, 2007

NL Rotations by ERA for 2007

EDIT: Upon further review, I don't like the way I originally came about these numbers. For some reason, I had simply averaged each team's FIP in each spot for the league numbers. A smarter way to do it would be to treat the entire league as one giant rotation and determine the top 20% of starts (generally around 518 for the NL and 454 for the AL) for spot #1, etc. It makes no sense to penalize the league average rotation because the top 15 pitchers are clustered on, say, 8 teams. This tends to lower the value for #1 starters and raise the value for #5 starters while leaving the middle guys generally unchanged. I've changed the numbers in the tables to reflect the new method. The "average" rotations at the end are the same as before. Sorry for the mistake.

A few days ago I had a post detailing rotations and average starters in the National League using FIP. Today I want to change gears, take off the beginner-sabermetrician's hat, and return to the commonly cited ERA. I admit, when I hear the phrase, "he's a #4 starter," I quantify that in terms of ERA and I would guess most of you do, too. ERA was the statistic used in the article that started me thinking about this "analysis" and it's common enough that I figured it would be worth a look today. I think the most interesting thing to take away from this exercise is the difference between perception of back of the rotation starters and their actual numbers.

As I did for the FIP table, each rotation spot is figured out the same way for each team (33 starts for #1, then 33, 32, 32, 32). Obviously I use ERA instead of FIP so for the Brewers, the #1 spot calculation looks like:
(6*2.06+17*3.74+10*3.82)/33 = 3.46 -- Carlos Villanueva, Yovani Gallardo, and 10 of Sheets' starts combine for the #1 slot.
The columns are similar to my last post: SERA is the cumulative starter ERA for the team and STDEV is the standard deviation of the starting rotation spots. Who would have thought, going into the year, the two NL teams with the most "even" rotations would be Chicago and Milwaukee? Ah, but enough of the preview, take a look at the table:

TeamSERA#1#2#3#4#5STDEV
San Diego Padres4.112.543.154.124.627.161.78
Chicago Cubs4.193.803.913.954.135.490.70
Arizona Diamondbacks4.233.014.084.304.726.481.27
San Francisco Giants4.243.383.864.094.475.700.88
New York Mets4.403.473.724.054.486.981.42
Los Angeles Dodgers4.433.033.584.245.356.631.44
Atlanta Braves4.453.113.324.185.527.231.72
Milwaukee Brewers4.553.464.244.815.165.200.73
Colorado Rockies4.583.804.214.334.876.060.87
Houston Astros4.713.214.444.755.266.291.13
Cincinnati Reds4.863.734.214.585.298.081.72
Philadelphia Phillies4.913.354.225.085.806.611.28
Pittsburgh Pirates5.023.763.955.115.857.411.50
St. Louis Cardinals5.043.574.114.865.697.531.55
Washington Nationals5.113.564.464.685.777.821.63
Florida Marlins5.584.645.135.215.817.671.18
NL4.643.293.97
4.505.127.031.43

A #4 starter in the NL this past season would have been above-average if he'd put up a 5.00 ERA. Similarly, a team would have to count its lucky stars if their #5 starter did the same. I mentioned it last time, but this table really points out how hapless Florida's starters were: only 37 starts all year were made by a pitcher ending up with an ERA (as a starter) of 5.00 or under.

As in the FIP post, here are the pitchers who threw ace-level or better in 20 or more starts (~3.46 ERA):
  • Jake Peavy, 34 starts, 2.54 ERA
  • Brandon Webb, 34, 3.01
  • Brad Penny, 33, 3.03
  • John Smoltz, 32, 3.11
  • Chris Young, 30, 3.12
  • Roy Oswalt, 32, 3.19
  • Tim Hudson, 34, 3.33
  • Chad Billingsley, 20, 3.38
  • Cole Hamels, 28, 3.39
  • Moving on to the #2 starters (~4.04 ERA):
    • Noah Lowry, 26 starts, 3.92 ERA
    • Carlos Zambrano, 34, 3.95
    • Tim Lincecum, 24, 4.00
    • Aaron Cook, 25, 4.12
    FIP liked Lincecum, placing him among the aces, but he slides to #2 status here. You can't be too disappointed for the rookie, though.

    Continuing the journey to #3 starters (~4.52 ERA):
    • Jason Marquis, 33 starts, 4.43 ERA
    • Tom Glavine, 34, 4.45
    • Jay Bergmann, 21, 4.45
    • Barry Zito, 33, 4.55
    • Justin Germano, 23, 4.56
    • Wandy Rodriguez, 31, 4.58
    It's far too easy, but I'm guessing this is not what the Giants signed Barry Zito for.

    Now we're into the hinterlands: #4 starters (~5.17 ERA):
    • Woody Williams, 31 starts, 5.06 ERA
    • Jamie Moyer, 32, 5.15
    • Dontrelle Willis, 35, 5.17
    • Chris Capuano, 25, 5.20
    • Dave Bush, 31, 5.20
    Not good news for Brewers fans here. At least you can say Moyer and Williams were showing their age, but it's never good when twenty-something starters struggle so much.

    The final stop on the ERA track, those disturbingly bad #5 starters (~6.77 ERA). I've got to go down to 15+ starts for this, as most teams won't put up with such mediocrity for long.
    • Kip Wells, 26 starts, 6.27 ERA
    • Adam Eaton, 30, 6.29
    • Tony Armas, 15, 6.40
    • Jason Jennings, 18, 6.43
    • Rick Vanden Hurk, 17, 6.81
    Those are some unpleasant numbers. His poor season didn't stop Vanden Hurk from being a celebrity guest at the clinching game of the Dutch Championship Series.

    To recap, the average NL starting rotation would be akin to this list:
    1. Cole Hamels
    2. Tim Lincecum
    3. Barry Zito
    4. Dontrelle Willis
    5. Rick Vanden Hurk
    Fold the Marlins into the Giants and you're 80% there!

1 comment:

Michael said...

This is a great post! Tim Lincecum is definitely the future of the Giants, along with Matt Cain. They've got a solid rotation long into the future with those great young arms.