like how much have the Leafs outperformed expectations, or how do they compare to other penalty kills? for the former, Leafs were expected to let in 7.81 goals against per 60 minutes of PK time, but ended up only letting in 6.11. that's about 22 more PP goals they should have allowed over the last 2 years with average goaltending.
for the latter, 8 expected goals against per 60 is the worst over that time frame, and 6.04 is the best. so Leafs are definitely a lot closer to the worst PK team than the best. it's a gap of maybe 10-15 extra goals against per year. Of course, the Leafs hardly ever take penalties so that helps