The O-Line took a major step back when Munchak wanted to coach elsewhere. According to Rod Woodson, NFL head coaches don't like a Hall of fame player coaching. Ben used to say he's got the yellow jacket. Munchak remains the only active coach that made the pro football hall of fame.
As for the OL, the Steelers are in trouble for 2021.
Pouncey is in decline and will probably retire when Ben does. Don't be shocked if he becomes a liability soon.
We have no proven left tackle besides big Al who a free agent next season. As our lone proven left tackle, losing him will hurt. As you might expect the Steelers have cap management issues with little room for maneuvering.
For some reason, the Steelers want to move Feiler to guard, and he's likely a goner in free agency as a decent starter in his prime.
Banner is the hope at Right Tackle, but I'm not convinced he's good enough to handle speed rushers. If he beats out Okoafor, a draft pick I didn't like, well chalk that one up as a bad draft choice.
Wisniewski is a stop-gap, short term solution.
Come 2021, the only good player the Steelers will have on the OL is DeCastro, and he's getting up there in age too. You just can't find a starting Left Tackle, a quality right tackle and a new center in one draft. More like several. While replaces will be found they won't be as good as Villanueva at Left Tackle, Pouncey at Center, and probably Feiler at Right Tackle.
How did it come to this? Well, how often have the Steelers spent first or 2nd rounds picks on the OL? Its been a while.
Like I said before, this is the year the window slams shut. Come 2021, the OL is taking a step backward.