This year the 25-year-old is stationed in the outer most locker among the catcher's section of veterans and prospects. It's the same spot the Geovany Soto occupied for several years as the Cubs' No. 1 catcher.
It is Castillo's spot now and he isn't taking that designation lightly.
"It means a lot but I am the kind of person that even though I have a job I am not going to be comfortable," Castillo said before Thursday's 8-3 loss to the Chicago White Sox. "I am going to play hard until I get the best out of me."
More than anything, he wants to stay healthy after several stints to the disabled list in recent years. He looked good against the White Sox despite going 0-for-3 at the plate as the 10,647 fans at HoHoKam oohed and aahed when Castillo made a behind the back catch near the White Sox dugout on Jared Mitchell's pop foul in the fifth inning.
Cubs manager Dale Sveum foresees Castillo, who took over the catching duties in the second half after Soto was traded to the Rangers on July 31, breaking the century mark in his first full year.
"You'd like to see Welington start out his first year playing every day, catch right around 100 to 110 games," Sveum said. "But that's subject to change depending on his own production and how things are going."
Against the White Sox, Castillo had a chance to catch right-handed starter Carlos Villanueva, who for one of the few times in his career knows he has a spot on the roster before the last week of camp.
The assurance lets him work on things a little more rather than competing. In his third outing of the spring, he totaled four innings while allowing six hits, two earned with no walks and three strikeouts.
"I had a very good bullpen (in between outings) and it carried over until today," Villanueva said. "I'm still struggling a little bit with my command. You take the hits. The home run Konerko hit (in the fourth inning) was a real surprise to me. I threw it exactly where I wanted, right there on his hands."
Sveum sees his veteran rounding into shape.
"He was sharper than he has been before," he said. "Other than (the Konerko home run) he had a really good breaking ball and command of all of his off-speed stuff."
White Sox starter Jose Quintana had a good start as he helped limit the Cubs to six hits. The right-hander went 3 2/3 innings as he allowed two hits, one earned on a Nate Schierholtz' first-inning RBI triple, with one walk and four strikeouts.
"I am trying to stay consistent and trying to prepare myself for the season," Quintana said through an interpreter. "I basically did the same thing as last start (3 perfect innings against Cincinnati on March 2)."
Cubs right-hander Scott Baker (Tommy John) threw a two-inning simulated game Thursday. His next step will be an appearance in a minor league before making his Cactus League debut around March 17. . Cubs infielder Brent Lillibridge has been out since Feb. 27 with a groin is expected back either Monday or Wednesday as is shortstop Starlin Castro (leg). . The White Sox and left-handed starting pitcher Chris Sale agreed to a 5-year contract worth $32.5 million with two club options.