"I really am," Tomlin said. "It's a waste of my time to focus on the guys that are not available to me, whether injury or otherwise. I tend to focus on the guys who are here and working. I think that's appropriate when you're in my position."
Under the franchise tag, Bell can't participate in offseason work unless he signs a waiver.
Left tackle Alejandro Villanueva hasn't signed his exclusive rights tender but signed a waiver for organized team activities and minicamp. When asked about Villanueva, Tomlin said he's glad he's on the field and getting better.
Bell's franchise tag is $12.1 million, but both sides are working toward a long-term extension and have until July 15 to complete one. Villanueva also is seeking an extension.
Bell, who's recovering from a groin injury, visited the Steelers facility two weeks ago but hasn't participated in any on-field work. Offensive coordinator Todd Haley said Bell has shown in the past he can miss time and be ready to produce once healthy.
Bell averaged a Steelers-record 157 yards from scrimmage in 12 games last season.
For now, that talent is not on display.
"I'm not getting into any of that -- attendance, excused, unexcused," Tomlin said. "The bottom line is the guys who are working are getting the opportunity to get better. Guys that aren't are losing that opportunity, for whatever reason that may be."