For about a 10 year period Michigan had a poor to average offensive line. Jim Harbaugh changed that and solidified both the offensive and defensive through recruiting, development, coaching, and the transfer portal. The gains the offensive line made got Sherrone the head coaching job at Michigan. That is the highest of honors.
Last year, the offensive line took a step back, maybe two steps back. They struggled with the run game and struggled in Pass Pro (outside their last two games). Yes, it was nice to see the line improve but they were below average to start the year.