The Pittsburgh Steelers most significant transaction heading into the 2015 season

When the Pittsburgh Steelers decide to make a change, whether it is in player personnel or the coaching staff, it is significant. Unlike franchises like the Washington Redskins who seemingly turnover their coaching staff and roster in three-year increments, the Steelers are the model of stability. Looking back on the offseason and the preseason to date, the team has made some significant moves, but which was the most important?

Some, like ESPN's Jeremy Fowler, will look at the acquisition of former Philadelphia Eagles CB Brandon Boykin as the most significant move for the black and gold. With second round cornerback Senquez Golson shelved with a shoulder injury indefinitely, the move looks to be tremendous as it adds a veteran presence in a very unsettled secondary. Boykin looks to be a difference maker in the team's secondary, even as a new player in a new system.

With the impending two-game suspension of Le'Veon Bell, and the train wreck which was the LeGarrette Blount experiment in 2014, the free agent pick up of DeAngelo Williams most certainly was significant. Williams is a veteran running back who isn't just extremely humble, but also has a pretty big chip on his shoulder. On top of that, he is a player who is used to sharing the load when he played alongside Jonathan Stewart with the Carolina Panthers. Williams will carry the load throughout Bell's absence, and will be able to provide quality depth when he returns from his suspension.

Believe it or not, but there are many fans of the Steelers who were ready to see Dick LeBeau leave. Some thought "Coach Dad" had run his course with the Steelers and it was time to move on, but this sentiment was't really breaking news. The question was will the Steelers have the guts to cut ties with the Hall of Fame player/coach? Turns out, they did just that and promoted long-time linebackers coach Keith Butler to defensive coordinator. Butler seems to have a willingness to mix things up while still having a great feel for his personnel as he has been with the team for a number of years. A new look defense could be just what the doctor ordered in 2015.

Sometimes extending the players on your current roster is as good as bringing in a new player, and they did just that with arguably their two best defenders in Cameron Heyward and James Harrison. Heyward had reached the 5th and final year of his rookie contract, and the team locking up the defensive lineman for the long-term is a huge step in the right direction for a unit in desperate need of leadership. As Heyward represents the young nucleus of the Steelers defense, Harrison provides depth and experience to the team. Harrison is in tremendous shape for the soon-to-be 37-year-old and will push Jarvis Jones for playing time and providing an explosive presence off the bench at the outside linebacker position.

All these transactions were great moves for the Steelers and the organization, but there is one which stands above them all, and that is extending Ben Roethlisberger's contract for another 5 years. Scoff all you want at this being the move important move to date, but with Roethlisberger about to begin the final year of his previous deal, the team did not want to even risk their Pro Bowl, two-time Super Bowl winning quarterback hitting the open market. With Roethlisberger, the Steelers are Super Bowl contenders...no matter what. Without Roethlisberger, well, the team is about as mediocre as it comes. In simple terms, Roethlisberger is the straw which stirs the Steelers drink. Without Roethlisberger, the Steelers aren't being talked about as AFC contenders, but just a middle-of-the-road team trying to keep Mike Tomlin's streak of non-losing seasons intact.

The Steelers don't make a lot of moves in the offseason and preseason, but they have hit all the right buttons up to this point. They might still have some moves up their sleeves, like signing left tackle Kelvin Beachum before the regular season starts, but even if they don't, keeping No. 7 in the black and gold for the remainder of his career is hands-down the best transaction the team has made in 2015.