Castillo entered Friday's Grapefruit League game against the Braves at Bright House Field without having shown much in his first two games since signing a Minor League contract on Monday, going 0-for-8 and making only a handful of plays in the field.
But he went 1-for-2 with two walks in Friday's 3-1 win, and he also looked good defensively.
"He has quick hands at second base," manager Charlie Manuel said. "He turned a double play."
"He's been OK," general manager Ruben Amaro Jr. said before the game. "It's hard to evaluate in two days. But he's moving around OK. It looks like he's in better shape than he's been in the last couple of years. We're assessing him. He'll get chances to play, and we'll see what we think at the end of the day."