Analyzing catcher defense has been a significant focal point in saber metrics for awhile now. Pitch framing has been one of the largest focal points, however that is something that we just don't have much data for in the minors.
Baseball America attempted to do that yesterday with an article ranking the top defensive catching prospects based on what information we do have. Now, this is limited to passed balls, caught stealing, and caught stealing rate. What they did was use the caught stealing totals and passed ball totals compared to league average.
The Astros landed three on the lists for the four full-season levels.
Tyler Heineman and Rene Garcia both landed on the Double-A list. Heineman came in at number three while Garcia was tenth.
Roberto Pena landed on the High-A list as the top defensive catcher. He had an astounding caught-stealing rate of 56.5%. That was the highest among all listed catchers at all levels. Interestingly, in the notes they mentioned he didn't have the same raw arm strength as others.