Over his last five games, Castillo is 10-for-21 with a pair of homers and five strikeouts.
"I've been feeling good lately," Castillo said. "I know I went through a tough [stretch]. I don't worry about it. I know I can hit a little bit. It's just time. It's going to come. If I don't hit, I'm good. If I hit, good. But all the time, I've got work to do behind the plate with my pitching staff."
D-backs manager Chip Hale said he thinks an opposite-field hit that Castillo had may have been what got him locked back in at the plate, but Castillo said he hasn't changed much.
"Not really," he said when asked about possible adjustments. "I think it's just time and confidence in myself. Just that hitting is going to come by feeling good and having good ABs and seeing the ball. I've had longer ABs, seeing more pitches. Don't try to think and everything is going to be there."
That philosophy worked well for Castillo on Saturday, and it appears he has a knack for big home runs against San Francisco.
Two of Castillo's 10 home runs this year have given the D-backs the lead in the seventh inning or later, and both were against the Giants. The other came April 20 off Madison Bumgarner at AT&T Park to help give the D-backs a 2-1 win.
Saturday, Castillo was the first hitter that Giants right-hander Hunter Strickland faced after being called upon with runners on first and second.
Strickland's first pitch was a slider that missed outside. Castillo fouled off a fastball to even the count, and Strickland then missed inside with a fastball.
The next pitch was a 95 mph fastball that Castillo hit into the bleachers in left.
"I wasn't thinking about hitting a homer," Castillo said. "His sinker is really good, so I was just trying to stay short and put the ball in play."
Castillo's blast ended the D-backs' six-game losing streak and for one night at least changed the mood in the home clubhouse.
"That's a huge hit for us right now," Hale said. "It's huge. It flips the whole thing around."