For newbies, the basic idea here is that at this point in the season, perhaps a better description of team performance is to be found in their Goals For/Against ratios than in their Win/Loss totals. Last season, a similar analysis I performed at this point sagely predicted that Ottawa was still a beast despite their sub-.500 record, and that the Boston Bruins, who at that time were in line for a playoff berth, were ready for a steep fall into NHL oblivion.
What I do here is look at Goals For and Against during regulation play (i.e. excluding shootouts and overtime), and look at how teams are earning points in the standings, compared to how many points the PythagenPuck formula would predict. For most teams, these numbers are quite close, but for the few outliers on each end of the spectrum, one can make the argument that wins or losses are about to pile up with increasing frequency unless something drastic changes on that particular team.
The table outlining all this has been made available over at Google Spreadsheets, something I'm finding to be a very useful tool for sharing information like this. The first few columns (GF, GA, Pts) come right from the typical NHL standings. Then we have OT/SO Wins, Reg GF (Goals For in regulation time only), Reg GA, Reg Pts (basically points in the standings not earned in OT/SO), Regulation Win %, Expected Win % from the formula, then the Difference between those two. Snarky comments come in last. Teams are sorted in declining order of Diff; in other words, from the most Overperforming team to the most Underperforming team.
So who's ready for a fall, and who's lurking in the weeds? It appears that the New York Islanders are the team playing highest over their heads at this point in time, somehow compiling a 9-6 record in regulation despite being outscored 44-42. Ottawa is also outperforming, but even if they regressed to the Expectation level they'd still win the Presidents Trophy handily, so no worries there. And in Phoenix, continuing down the path they're on could lead to another Western Conference last-place finish, but we'll have to see how the addition of Ilya Bryzgalov affects the team.
On the underachieving side we have primarily the Buffalo Sabres, who apparently do miss those guys Briere and Drury, but at least shouldn't be the worst team in the Eastern Conference as a result. Then we have two teams in the West which could make serious noise this season; the Columbus Blue Jackets are playing like an old Dallas team under Ken Hitchcock, and only a 0-4 OT/SO record is holding them back from garnering greater attention for their rise through the standings. The San Jose Sharks are also playing better than their record indicates so far, and in fact their GF/GA ratio in regulation surpasses Detroit for the best in the West.
What this analysis assumes, of course, is that a given team's performance in terms of GF/GA will remain relatively constant, and that the wins and losses will shake out accordingly. But as we know, dramatic swings can sometimes take place due to injury (as when Anaheim got hit with concurrent injuries to Pronger, Giguerre, and Beauchemin last year) or by a coaching change (St. Louis before and after Andy Murray looked like two different teams, much like Atlanta appears this season). This tool can be a useful signal to action for teams like the Islanders that they shouldn't get too comfortable with their early success, or serve as a reason for calm in places like Columbus where there's every reason to believe that they're on the right track.