His past performance was dictated by being put in a primarily defensive role with at least one offensive boat anchor. We have never been deep and/or healthy enough that Barbashev didn't have a Clifford or MacMac on his line beofre this year. He was always the secondary defensive line. RoR got the other team's best line and Barby/Sunny got the defensive zone starts against the 2nd line. He is 7th lowest Ozone start amongst Blues from 17/18 to 20/21 (at least 200 min). He is amongst guys like Torburn, Brodziak, Upshall, Jaskin. He gets the deployment of a 4th liner. But there is a reason he is paid really well for a 4th liner, because he produces better than those guys despite his role.
This year, he is getting top 9 deployment. Partially because of how deep we are. We can actually role 4 top 9 lines, but also because he clicked on the line with Tarasenko. He is for the first time ever, getting more O-zone starts than D-zone starts, having 2 competent offensive guys on his line, and getting a sliver of PP time. In the past 9 games, Barbashev already has 25% as much PP time as he had the previous 3 years. He is producing now because of he is getting the opportunities to now. Its not that suddenly he took a giant leap forward in skill at 25.