You guys touched on some good positives. I have a few to add:
I love Randy Fichtner. He's for real as an OC. His playcalling was a boon to the offense. Ben with a career high passing. Over 75% in the red zone, 2 1000 yard receivers. Just a few costly turnovers stopped this team from having a chance in the playoffs. If a change happens at HC, you can still keep Fichtner, and keep the consistency with Ben. That will be very important if a change happens.
Ryan Switzer. He was a great piece of that helped the Steelers gain a valuable PR, KR and skatback/slot receiver. What a nice pickup to help move the chains. He doesn't break plays open, but he works hard every play, and will do whatever he can to help his team win.
I'm not sure where he ended up in stats but just as you say, he does his best and tries as hard as anyone out there. His attitude and perseverence would be well mimicked by other players would serve them well.
A couple honorable mentions: Hargrave, Sutton, and Sensabaugh all improved down the stretch, and played some great defense. You want to see that in a young D, and we're starting to get some returns to the investments. I think Butler still is a problem, and needs replaced, because the talent is there to win games against top teams (See NE and NO). They also did a great job this season of mitigating points after turnovers, but just couldn't generate any themselves.
ABSOLUTELY he needs replaced. I'm not sure of who's in charge of the current "D" if Butler or CMVLT but either way it is a tired scheme. A new DC with control would do this team an amazing turnaround. You're right as the talent is there but the coaching has failed the talent. One more step and this should happen regardless and that is for Mr.Joey Porter to take his leave. Friend of the coach or not, he needs to go.