The Pirates second baseman, who was named the Bank of America National League Player of the Week on Monday, roughed up Brewers pitchers for nine hits, four home runs and 14 RBIs in a four-game series that began on May 29.
Milwaukee's Chris Capuano threw a high, inside pitch to Castillo in the second inning of Wednesday's game, but Castillo's approach went unchanged. The results Castillo had been experiencing wouldn't change either, as he homered later in the same at-bat.
"[The brushback pitch] seemed to have no effect on him," Capuano said after the game. "He's just unconscious right now, on another planet. There's no way he's that good."
Castillo did his best to prove just how good he was all week, hitting .478 and leading the National League with 15 RBIs.
Castillo extended his home run streak to five straight games during the week, but couldn't match the six-game streak posted by teammate Jason Bay from May 22-28.
Was Castillo trying to do one better than Bay this week?
"Yeah, maybe," Castillo joked after a two-home run performance on Tuesday. "I've been watching him."
Castillo obviously watched and learned, bringing Pittsburgh its third straight National League Player of the Week award. Bay won the award the previous two weeks.
Castillo's manager wasn't surprised at the recent power outburst by a player who had hit just two home runs this season prior to his five-game streak.
"It's there," Jim Tracy said of Castillo's power on Wednesday. "There's a lot of it there. The only thing is it won't come out if you're swinging at bouncing breaking balls."
"His preparation to play has improved greatly and ... he is making people throw the ball over the plate."
Castillo wasn't the only Pirate up for the award this week, with pitcher Zach Duke (2-0, 3.68 ERA, 9 Ks) and infielder Freddy Sanchez (.520, 2 2B, 3 RBIs) also being nominated.
The Pirates have benefited from the play of their young stars, going 7-3 over their last 10 games.
The Padres' Chris Young (2-0, 0.00 ERA, 12 Ks) and the Diamondbacks' Eric Byrnes (.296, 4 HR, 6 RBIs) were a couple of the players outside of Pittsburgh nominated for the award.
Ryan Crawford is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.