Castro was hitting .253 (18-for-71) in 22 starts entering Thursday.
"My at-bats have been pretty good for the most part," Castro said. "I'm just trying to iron some small things out and get back to where I was in Spring Training. It's all about getting timing back. Obviously, pitching is a little bit different in Spring Training than it is during the regular season, so getting back into that regular-season mode has been a little bit more of an adjustment.
"I'm really good with where I'm at and my swing feels really good. Hopefully I can start putting together some good games in a row."
Castro, of course, still has fewer than 300 Major League at-bats to his name after missing all of last season following knee surgery.
"I don't know where I could be if I hadn't missed that time, but honestly I don't feel like I missed that much time," he said.