added 5/2/2008 by Scott Barzilla
I realize it's been awhile. This is usually the point where the critics throw in their customary, "thank God!" Things have been busy. TAKS is going on in the public schools and this is always the time of year to look for possible promotions. Meanwhile, baseball fans and analysts want to avoid making the kind of knee-jerk prognostications that people make this time of year.
This is where we can split the game into two distinct groups: those on the outside and those on the inside. Those on the outside love surprises. It's what makes watching the game and covering the game worthwhile. Teams like the Rays, Athletics, Marlins, Cardinals, and White Sox create the unpredictability that we love. Insiders don't like unpredictability as much. They want to predict the future with increasing accuracy.
This is where statistical analysis comes into play. All teams use it whether they want to admit it or not. The question is what do you use. Sabermetricians have been working long and hard to develop formulas to accurately grade past performance. Why would they waste their time? Well, if we can accurately grade past performance then we can also accurately grade current performance and predict future performance.
Old-fashioned teams use statistics like runs, RBIs, HRs, and batting average. They use statistics like ERA, strikeouts, hits, walks, and WHIP. These numbers have worked well over the years, but sabermetricians think we can do better. Whether you exist in the old-fashioned or the new wave, there are two schools of thought that dominate the game.
Some teams utilize what we might call "performance scouting." Essentially, who a player is is what he has been in the past. You take an average that might go back three or five years and use that as a way to accurately project performance for the future. Other teams utilize what we might call "projective scouting." They envision what a player can be. There are a number of ways to do this. Most systems utilize a system that plots out data in what would look like a bell-shaped curve. At a certain point, a player reaches his peak and starts to go downhill.
In essence, a player that is turning 26 or 27 is going to be better than he was then when he was 23, 24, and 25. Therefore, if you go by the three year average you are shorting him. The same is true in reverse for the 38 year old. Different systems use various rates of ascension and decline to project numbers.
We could get into a host of different projection systems, but that belies the point. When you look at the current teams and their projections, you can see some stark differences between the performance scouting and the projective scouting. In some instances, one can look a lot more like what the team is currently doing. I will not throw out any data this time because it is way too early. I am in the process of preparing a study on the effectiveness of projection and performance scouting.
For our purposes here, I am using PECOTA from Baseball Prospectus, but that isn't to say that PECOTA is better than Marcel, Bill James, or CHONE. This is more about whether teams are better off using projections or past performance. I'm sure the results will be interesting for the Astros and the rest of the teams.
Check out my blog at http://commons.chron.com/barzilla