Not to mention his secondary scoring!Statistically the biggest difference is high danger save percentage. Last season, in all situations, Ullmark had a .824 high danger save percentage, 22nd among goalies who played 1000+ minutes. This season that has improved to .865, 4th among goalies with 1000+ minutes behind Sansonov, Swayman and Kochetkov (who has only played 19 games). Swayman's high danger turnaround has been far more drastic, going from .802 last year to .881 this year.
I don't know enough about the technical points of the position to identify exactly what Ullmark and Swayman are doing different. All I would do is tip my hat to Goalie Bob. There's a reason he's been here forever and we never usually have goalie problems. Last year an "average" season was a bad one by previous standards set.