It’s part of the NFL, according to the Pittsburgh Steelers. PITTSBURGH — The Pittsburgh Steelers understand who Diontae Johnson is on the field, and because of that, their wide receiver one and his lack of opportunity this season isn’t a concern. Head coach Mike Tomlin addressed Johnson’s lack of targets, explaining that teams are taking him out of the equation for the Steelers. “Let’s be frank, okay? Diontae is a known commodity within the group. People are going to have an agenda to minimize his impact on the game, particularly in significant moments, possession-down, redzone football,” Tomlin said. “When you’ve…