By Alek Arend The Pittsburgh Steelers have released their first depth chart of the preseason. Mitch Trubisky, as expected, is currently the team’s starting quarterback. First-round pick and former Pitt star Kenny Pickett, meanwhile, begins at the No. 3 spot on the team’s quarterback depth chart. The experienced Mason Rudolph is currently the team’s backup. Pickett isn’t expected to contribute much for the Steelers this upcoming season. He can study from the sideline while Trubisky likely runs the show. It’s also an advantage to have a veteran in Rudolph in case Trubisky goes down. Here’s a loo…