A while back, I decided to try to figure out why the Leafs seem to have so many problems killing penalties year after year. Over the past few weeks, I've gathered some data and watched a bunch of video to try to piece it all together. I had no intention of looking at this from any kind of shot quality angle, but in the end, I think it's what I've found. It's actually divided into two parts, and I apologise for it being pretty long (about 3000 words between the two pieces). I'll quote my own conclusion here, and then link to the two posts.
We know from Part 1 that both teams [the Leafs and the Wild] give up shots on the penalty kill at roughly the same rate (Minnesota gives up slightly more than Toronto). We also know from Part 1 that both teams face shots from the same locations at roughly the same rate (with Toronto once again looking slightly better). However, the Leafs clearly allow goals on the penalty kill at a far more frequent rate than Minnesota does. And after watching the tape to see why that is, it seems pretty clear to me that there are significant structural differences in the way that each team kills penalties that results in Toronto giving up more goals. Perhaps an easier way to say that is this - a shot against the Leafs from a given area on the ice is far more likely to be a good scoring opportunity than a shot against the Wild. While both teams give up a similar rate of shots from similar areas, a shot faced by a Leafs' goaltender on the PK is frequently much more difficult to stop than a shot against the Wild from the same spot. And if I'm not mistaken, that's shot quality.
Part 1 - looking at goaltending
Part 2 - looking at systems