Including the previous year when Lewis wasn't on the team and the PK as a whole was a nightmare doesn't make a lot of sense.
Sorting by GA/60 for looking at PK numbers isn't ideal since it doesn't account for goaltending variance (among several other factors), but I'll play. Here's last year:
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- Lewis did not lead the team in GA/60 at 5 on 4. This includes an on ice save percentage of 93.57%, which was highest among all forwards except for Lizotte. A number that also doesn't seem realistically sustainable on the penalty kill especially. Seeing that, it looks like he prevented a lot of scoring chances/high danger chances, right? Trevor Moore gave up FAR more goals/60 on the PK, but less scoring chances against. Why? Because the on ice save percentage for him was 86.29%. There wasn't a significant difference in high danger chances against/scoring chances against/or xGA between the two, even with Moore being slightly better in some categories. It came down to goaltending variance. You can see that in the HDGA/60 column.
- Kopitar (who should not be killing penalties) and Danault were the only two forwards with worse SCA/60 data.
In xGA/60, only forward that was worse was Kopitar.
There is no data to support that Lewis was particularly good, and saying "eye test" is just handwaving away what actually happened. At best you can say Lewis was a replacement level penalty killer.