What was the biggest offseason mistake the Steelers made?

After training camp, Detroit Lions cornerback Cam Sutton speaks with reporters in Allen Park on Tuesday, July 25, 2023.

The Pittsburgh Steelers have five games under their belt, and their issues are obvious and harsh.
Most people would concur that the Steelers aren’t as good as their record suggests, even though they have managed to secure a 3-2 record.

When considering the past offseason, it is simple to identify certain areas in which the team could have performed better, but it is more difficult to identify the single biggest error made.

The first choice—and the one that the majority of supporters will make—is to retain Matt Canada as offensive coordinator.
Head coach Mike Tomlin demonstrated his commitment to Canada by sticking with the offense despite the previous season’s struggles.
What we’ve observed is that the offense is still having trouble and doesn’t appear to be improving.

One obvious roster change sticks out when looking at it from the perspective of a player.
Pittsburgh decided that signing Patrick Peterson would be a suitable substitute for cornerback Cam Sutton, and made no attempt to keep him. Sutton is a star for the Detroit Lions, and Peterson has struggled, so this hasn’t been the cast.

And lastly, the way the Steelers performed in the preseason is perhaps something that people are considering.
The Steelers starting offense was so good that everyone had an illusion of it because they only played three games and five series.
Maybe some of these issues would have surfaced and fixes could have been made before the regular season began if Tomlin and the coaches had given the Steelers starters more playing time.