The Kings have been a one-line team, but that's no cause for concern
As an astute observer of all things Kings, I've noticed that the Pearson-Carter-Toffoli line has been running hot lately. To say they've been the Kings' entire offense is almost literally correct. The Kings have scored 21 goals this year. Carter, Pearson, and Toffoli personally scored 16 of those, and got primary assists on 2 of the others. TSN's Scott Cullen ran the numbers and found that no team in the NHL is more dependent on one line for scoring.
Combine one absurdly productive line with three other equally unproductive lines and you pretty much get a league average offense. The Kings currently sit at 14th in 5v5 scoring rate. Their power play is its usual mediocre self, ranking 21st in scoring rate and 23rd in shot generation.
Those numbers really aren't bad news. 14th in 5v5 scoring is way better than the Kings usually do (they're 26th over the last three seasons combined). Moreover, since the hiring of Darryl Sutter the Kings have been the preeminent defensive team in the NHL. They have a long track record of severely limiting shots and goals against, which means a league average offense is all they need to be a great team.
But there must be doubts about whether the Kings can sustain this mild offensive success. All their goals are coming from three forwards. When that line slows down, aren't the Kings in trouble?
The bad news is that Pearson-Carter-Toffoli will indeed be unable to keep this up. The line's scoring pace is going to decrease dramatically. With Toffoli on the ice, the Kings are shooting a cool 19.05% at 5v5. That's more than double league average (typically about 8%). Sidney Crosby drives sh% far more than any other NHL player and has a career 5v5 on-ice sh% of 11.24%. Pearson-Carter-Toffoli are great, but I don't think they're as good offensively as Crosby - and even if they were, they couldn't sustain anything close to 19%.
Another approach is to look at personal shooting percentages. Pearson, Carter, and Toffoli have collectively scored on 16 of 52 shots (30.7%). All three almost certainly have true personal shooting talent of under (probably way under) 15%. Regression is coming. Long-term, the line can probably sustain a scoring rate a little under half of what they've accomplished the first eight games.
None of that is to say the line hasn't been awesome. Pearson-Carter-Toffoli are putting up a 59% Corsi together, a number all the more impressive considering the Kings as a whole have not put up their usually excellent possession numbers (a topic for another post). All three are among the Kings leaders in shot generation. They are an excellent line that's had unbelievable shooting luck, and even when the luck wears off the Kings can still expect quality play from those three. Just not quite two-goals-a-game quality.
Fortunately for the Kings, regression works both ways. While Pearson-Carter-Toffoli are on the top of the on-ice sh% leaderboards, many unfortunate Kings lurk near the bottom, including Anze Kopitar (3.64%), Mike Richards (3.12%), Dustin Brown (2.56%), and poor Kyle Clifford (0.0%). All those guys except Kyle Clifford have real scoring talent and are going to turn it around soon. (Kopitar's bounceback may be delayed a bit by injury, but he isn't expected to miss more than one game.) The eventual return of noted sh%-driver Marian Gaborik will help, too.
These two regressions, I think, will basically cancel out, and the Kings will be able to sustain an offense that's league average or slightly better. Doing that will require the Kings to shoot for a decent percentage, something they have not done over the last three years (in fact, they are dead last). I am hopeful the Kings can do that because a) shooting percentage is highly random even over large samples, so to some extent the Kings' shooting woes have probably been bad luck, and b) the Kings have recently improved the roster with offensively-talented players like Gaborik and Toffoli. The offense should stay decent, which is all it needs to be.
Two more quick points about Toffoli-Carter-Pearson. First, while their sh% success will dry up, it may nonetheless have salutary long-term effects if it convinces Sutter to give the line more ice time, because the line is still excellent without the shooting luck. Sutter still seems hesitant to fully trust his young players. Toffoli and Pearson each have less 5v5 ice time than Kyle Clifford and way less than Dwight King, which seems…. wrong? The sooner that changes the better.
Second, it should go without saying that just because Toffoli-Carter-Pearson have had great luck so far does not mean they are due for a cold streak now. Going forward, they have the same likelihood of undergoing good or bad luck as anyone else on the team. But the principles of probability dictate that, as with all NHLers, their on-ice shooting percentages will gravitate towards roughly league average over the long run.