After a disappointing loss to Tim Tebow and the Denver Broncos in the playoffs, the Steelers were forced to part with team leaders Hines Ward and James Farrior.
Mike Tomlin then decided that the offense needed to shake things up and hired former Kansas City Chiefs head coach Todd Haley to replace Arians.
What this means is more pressure on Tomlin to make all the pieces work. With a tough schedule in 2012 to go along with perhaps the toughest division in the NFL, Tomlin will have his work cut out for him.
However if we have learned anything from the past five years, it's that there is no challenge too big for Tomlin to handle.
After all what could be more challenging then replacing a Hall of Famer who just won the Super Bowl, as a 35-year-old first-time head coach?
Tomlin has been one of the best coaches in the NFL from day one, with a remarkable 55-25 overall record and one Super Bowl win in two appearances.
Here are five reasons why Mike Tomlin will be the NFL's best coach in 2012.