Lehtera is lost in St Louis, but he was a ppg his last two KHL seasons, and had 37 ES points in his first year in St Louis.
He was included as a salary dump, but there's enough there to gamble you can turn his career around for his next two seasons.
The condition is if it's a top 10 pick, St Louis can move it to 2019, if again a top 10 pick, they can move it to 2020 by giving up a 2020 3rd rd pick.
Schenn was a first rate PP scorer who was llimited at ES, Hextall may have felt his value had peaked and wanted to move him before the league figured that out.