About a week ago, I put up a post on team even strength shooting percentage, which included a chart showing what the underlying talent distribution in that area probably looks like. I've reproduced the relevant curve below:
The curve isn't excessively narrow. The 97th percentile equates to a shooting percentage of 0.0902, meaning that, in an average season, the league's most talented EV shooting team would have an underlying shooting percentage at or around that mark. That's no trivial advantage - with neutral luck, such a team would be expected to score roughly 18 more even strength goals than a team with average EV shooting ability.
The problem is that, given that goals in the NHL are somewhat of a statistical rarity, the regular season doesn't provide us with a sample that is sufficiently large so as to be able to identify each team's true talent level with reasonable accuracy.
This estimate uncertainty is well illustrated by comparing last year's Devils, who had a league worst 0.065 EV shooting percentage, with last year's Stars, who posted the league's best mark at 0.089. That seems like a fairly large gap - almost 2 and half percent. Surely one would be able to conclude that the 2010-11 Stars possessed more EV shooting talent than the 2010-11 Devils?
In fact, there is a not-insignificant probability that the Devils were actually the better EV shooting team. This becomes immediately apparent upon viewing the ability distribution for each team and noting the overlap between the two curves.
There is an 11.6% chance that N.J was actually the more talented team last season in terms of EV shooting ability. In other words, there will be some seasons - of which 2010-11 is an example - that do not permit the conclusion that any single team has definitively more EV shooting talent than any other.