Bell has yet to play for the Steelers (5-2-1) this season as he seeks a long-term deal. The 26-year-old running back hasn't signed his $14.5 million franchise tender and has until Nov. 13 to report if he wants to play this season.
"Why waste more energy on it?" the 28-year-old DeCastro told The MMQB following Pittsburgh's 24-16 victory over the Baltimore Ravens on Sunday.
"The first week, we were shocked by [the Bell holdout]. At this point, what are you gonna do? Sit here and drive at it and beg him to come back? Obviously that's not how it works. So we just put our best foot forward and try to do the best for this team."
DeCastro's comments came on the heels of head coach Mike Tomlin telling a reporter that "we need volunteers, not hostages" in response to if the Steelers need Bell in the lineup.
Bell's replacement, James Conner, has rushed for 706 yards and nine touchdowns. The 23-year-old also has 38 receptions for 379 yards and a score.
"It just doesn't matter," DeCastro said. "If [Bell] shows up, you're blocking your guy the same as you would for Conner. It's not like it's going to be an issue. As much drama as there was with that, it's not going to affect how we play football."