In looking at the Flames seasonal percentages, I noticed that Vic's timeonice app was delivering a different ES SV% than the one stated in Desjardins study. In fact, the underlying shot and goal totals were different for each. Vic's site had Kipper seeing about 170 more shots and allowing three more goals than what Desjardins accounted for. As a result, Kipper comes out with a better SV% (90.9) in the former.
Unable to resolve the differences myself, I emailed Desjardins for some clarification. His response was:
Some possible differences:
- Vic includes 4-on-4 and 3-on-3 (this is certainly the biggest difference)
- Vic uses just the NHL.com data; in order for me to get shot
location, I need to combine ESPN with nhl.com. I've audited it in the
past and it looks like they have the same dataset, but there are some
mismatches
- Vic determines the number of skaters directly from the NHL.com
play-by-play (PL) whereas I pull it from the TOI charts (TV and TH).
For whatever reason, they're different.
- Neither one of us includes empty nets
So, seems to be differences in category and reporting source. Technically, then, Kipper's SV% at behind the net (89.9) is his "true" 5on5 save rate (as close as we can get with the data in question, I guess), while Vic's site is Kipper's "true" even-strength SV% across all such variants of that condition.
As of right now, I'm unsure which should be consider more reflective of a goalie's ability.
