Daily Archives: March 16, 2007

Similarity Index and Comparable Players

If you’re a subscriber at Baseball Prospectus, you know all about similarity index and comparable players. If you don’t know, here is a real brief summary. Basically, the backbone of this is the PECOTA system, and is broken down into four main attributes; on field production, shear amount of numbers, physical traits like handedness, and then finally defensive position. The database contains over 20,000 seasons from major leaguers since World War II, as well as 10 years worth of minor league seasons from 1997-2006. Similarity index is basically a snapshot of all of the player’s comparable, with an index of 50 being a very common player, historically speaking, and a rating lower than 20 meaning the player is very unusual in a historical context.

Just for fun, on this miserable looking Friday, I looked at the comparable lists for the Phillies 10 best prospects, according to my prospect grades I did a little while back. Here are just a few brief thoughts on each guy.

1. Carlos Carrasco: SI = 57. At this point, his ten most comparable pitchers isn’t a pretty sight, but near the bottom of the top 10, then the 11-15 range, you see names like Jeremy Bonderman of 2003 (#7) and Yovani Gallardo of 2006 (#12). Because he had such a night and day change from 2005 to 2006, it’s tough to project him. The upside is definitely there.

2. Adrian Cardenas: SI = 24. Lots of interesting guys in his Top 20, including David Wright (#3), Ian Stewart (#13) and Milton Bradley (#14). Again, we’re dealing with a small sample size, hence his low Similarity Index.

3. D’Arby Myers: SI = 7. Clearly, because he was only 17 in the GCL, he’s a somewhat unique case. However, numbers 8-10 on his list include Carl Crawford, Jose Reyes and Carlos Gonzalez, one of the best prospects in baseball.

4. Scott Mathieson: SI = 66. Mathieson’s top 20 is all over the map, but does include a few really good signs, including Jake Peavy circa 2004 (#3) and Catfish Hunter circa 1969 (#7). However, it also includes guys like Victor Santos and Seth Etherton. We won’t really know anything about his future until sometime in 2008.

5. Josh Outman: SI = 59. Outman’s top 20 is absolutely ugly in every way. He really turned things up in 2006, and he was outstanding over the last 6 weeks of the season, but he still has control issues. We can only hope his list looks better at this time next year.

6. Edgar Garcia. No comparables in the PECOTA system yet.

7. James Happ: SI = 62. Happ’s top 20 is ugly as well, but interestingly, Doug Davis circa 2000 is his #3 comparable. Prior to Happ adding velocity on his fastball, he shared a lot of similarities to Davis. You could do worse than Doug Davis, who is a capable innings eater, but with a strong 2007, I’d imagine Happ’s comparable pitchers list will change a bit.

8. Joe Bisenius. No comparables in the PECOTA system yet.

9. Dan Brauer. No comparables in the PECOTA system yet.

10. Ben Pfinsgraff. No comparables in the PECOTA system yet.

Since a few guys aren’t in the system yet, I figured I’d look at a few lower ranked prospects and see how they stacked up.

Matt Maloney: SI = 60. Doug Davis circa 1999 comes in as his #2 comparable, and Brian Fuentes circa 1999 his #7 comparable.

Michael Bourn: SI = 49. The 2004 version of Tim Raines is his #4 comparable, and the only guy that looks anywhere near decent is Randy Winn circa 1998, who is his #15 comparable. Maybe this helps affirm my worries about him being a regular player in the big leagues.