The Astros shut down Castro following the Arizona Fall League's Rising Stars game out of concern for his workload since February.
The highly-regarded catching prospect began the season at spring training in Kissimmee, Fla., and along the way played home games in Lancaster, Calif., Corpus Christi, Texas, and Peoria, Ariz. He also attended World Cup team training in Cary, N.C., then played in the World Cup in Germany and Italy.
"Obviously this was the most I've ever played before," Castro said. "It was a good challenge to see what the rigors of the season were like."
But it wasn't just jet lag that caused his numbers to lag by the end of his first full season, which spanned nearly nine months.
Including all-star games, Castro played in more than 140 games, almost exclusively behind the plate. He hit .130 in the World Cup and .143 in the Fall League before the Astros pulled the plug.
"It wasn't a very difficult decision," assistant general manager Ricky Bennett said. "Most players won't admit when they're tired. Just watching him play and putting together the numbers, it was obvious."
The Astros were pleased with the progress of the 22-year-old Castro, the No. 10 overall pick in 2008 out of Stanford. He hit .300/.380/.432 between high Class A Lancaster and Double-A Corpus Christi. A lefthanded hitter, Castro displayed good gap power this year and posted a solid 55-76 walk-strikeout ratio in 446 at-bats. Defensively, he progressed in his game calling and threw out 45 percent of baserunners.
Up next is an offseason regimen that will start in the weight room as Castro recovers from the season back in his native California.
"I'm not going to do much training for baseball until around Christmas," Castro said.
And after that, he'll go to spring training and compete for a big league roster spot.
• A strong finish helped outfielder Jon Gaston finish with .239/.358/.457 numbers in the AFL. However, Gaston also struck out 38 times in 92 at-bats.
• The Astros added shortstop Wladimir Sutil and lefthander Fernando Abad to their 40-man roster to keep them from leaving via minor league free agency. Sutil batted .273/.348/.324 for Corpus Christi. Abad spent most of the year at Lancaster with a 4.14 ERA and a 79-8 strikeout-walk ratio in 83 relief innings. He became a starter upon his promotion to Corpus Christi, posting a 3.21 ERA in three starts.