Monday, January 18, 2016

Astros Depth Charts: the Primer

This has proven to be a very odd baseball offseason, with a slow market for a seemingly bumper-crop of free agents developing.  The Astros don't seem to be aggressively pursuing any significant free agents, mostly because they have a young roster with a strong minor-league system.  If they were, we probably would not hear about it because the front office is famously tight-lipped.

So, to whittle away the time, a few of us have gotten together to publish some Astros Depth Charts.  The idea is that we would have a quick look at all players on the 40-man, including their performance in recent seasons.  We would look at the various publicly available projection systems to try and determine what value the Astros could get from each player.  We would try to include relevant players not on the 40-man roster, but who were solid contributors at AA and above in the 2015 season.  Batguy plans to release his annual projections toward the end of this exercise, which will probably coincide with the start of Spring Training.  A couple of the positions will need two or three articles to cover them adequately.

One spinoff of doing these depth charts is that my understanding of the various projection systems and WAR calculations has been enhanced.  We used Marcel (from, Steamer (from and ZIPS (written by Dan Szymborski and also published on Fangraphs) for the projections.  Marcel is the simplest of the systems - it projects purely on the basis of regression to the mean on the last three years of MLB data, accounting for the age of the player.  Steamer and ZIPS are proprietary systems, and the method by which their projections are calculated are not easily publicly available.  PECOTA was not used.  No projection system is perfect, but for the purposes of comparing and ranking players - especially those who haven't yet appeared in the major-leagues - I found them to be very useful.

Of course, if the projection systems were perfect, we wouldn't need to be troubled watching the actual baseball, and we could just decide a winner on the projections.  But that would be no fun.  But the sparing of the inevitable emotional roller-coaster would certainly be great.

So, anyhow, scroll on down, and read the first exciting instalment of the Astros Depth Charts for 2016.  First up: the Catchers.  Comments, as always, are welcome.  We plan to publish twice a week.  We should wrap up around the time that Spring Training starts, so perhaps this will provide us with some discussion material through the last painful month before we get to talk about ACTUAL baseball again.