I was thinking about the starting rotation for the Tigers and how lucky they really were in ’06 to have a pretty stable rotation. I know they lost Maroth but Zach Miner stepped in and held his own until the very end when Ledezma got a few starts. So having a total of 7 starters throughout the year was rather unique as most teams likely had a few more than that.
When looking at who was going to be the Tigers #1 starting in ’07 I started wondering what being #1 really means, if anything at all. My classic understanding of what a #1 starter was vs #2, 3, etc was that you had your best guy at #1. Doing so through the season, I thought, would pair up your # 1 vs the competitions #1 starter. But many issues get in the way of this actually happening whether it is off days or changing starters in/out due to performance or rest.
I wanted to better understand how often pitchers really faced each other for the Tigers so I took a look at 2006 statistics that I pulled from Retrosheet. I initially looked at how many unique starter/starter pairings were seen throughout the year, but this isn’t really fair as there are many teams the Tigers only played for one series leaving no chance of a repeat match up. So I then looked at each Tiger starting pitcher individually and weeded out the games where the pitcher started against the opposing team only once. This allowed me to then get a much better understanding of how often, within actual opportunities, a Tiger pitcher saw the same pitcher on a given opposing team thus getting some idea of how stable rotations are for both the Tigers and the teams they faced.
Here is what I found.
Here is a key for the columns on the data below:
- Tp>1 – Teams played more than once
- SaTp>1 – Starts against teams played more than once
- Upf – Unique Pitchers Faced
- Pf>1 – Pitchers faced more than once
- %Re – Percent Rotation Effeciency
%Re is calculated by 1 – ((Upf-Pf>1)/SaTp>1). This measures the percent of starts where a pitcher saw the same opposing pitcher limited to only times where such a match up was possible.
For Miner, Maroth and Ledezma these don’t really mean much as they had so few starts but for their other starters these numbers were rather low. Each stable rotation member on the Tigers had roughly the same number of chances to start against a team more than once as well as roughly the same number of times it actually happened but Kenny Rogers faced only faced the same pitcher 55.56% of the time.
This is only looking at the percentage of repeat match ups and not whether we actually got #1 vs #1 match ups. A teams #1 guy tends to change throughout the season and sometimes it works out even when you don’t get it. For instance, and one of my favorites from 2006, was the Miner vs Liriano match up that happened twice and Detroit won both.
What factors should go into making your rotation at the beginning of the year? I’m not really certain on that one. I looked at Home vs Away and personally looked at many other statistics that should go into the rotation and nothing is all too compelling.
I’m curious as to every one else’s thoughts as to what makes a good starting rotation?