The Vegas Golden Knights are not a one-line team, but one line will worry the Sharks most in the second round.
The top trio of William Karlsson, Jonathan Marchessault, and Reilly Smith was one of the league's best this season. Only Colorado's Gabriel Landeskog, Nathan MacKinnon, and Mikko Rantanen were on the ice for more five-on-five goals together in the regular season (47) than Vegas' first line (46), according to Corsica Hockey. In just under 700 five-on-five minutes together, they controlled 55.54 percent of the shot attempts, 56.55 percent of the shots, 56.41 percent of the expected goals, and two-thirds of the goals, outscoring opponents 46-23.
They did so playing primarily against the team's top players. According to HockeyViz, Karlsson, Marchessault, and Smith spent an above-average amount of time matched with their opponent's top-four forwards and top-three defensemen. Per Corsica, no Vegas forwards faced competition that accounted for a higher percentage of their team's ice time, a higher percentage of shot attempts, or a higher percentage of expected goals in the regular season.
Golden Knights head coach Gerard Gallant continued to use them this way in the first round against the Los Angeles Kings. They were attached to the hips of Los Angeles' top line, playing nearly an hour of five-on-five time against Anze Kopitar alone, according to Natural Stat Trick. Kopitar's next-most common forward opponent, James Neal, played only 15 minutes against him five-on-five in the entire series.
When the Sharks and Golden Knights face off in Sin City later this week, Karlsson, Marchessault, and Smith will undoubtedly see a lot of San Jose defensemen Justin Braun and Marc-Edouard Vlasic. Gallant will likely primarily ice his first line against Peter DeBoer's top trio of Joonas Donskoi, Evander Kane, and Joe Pavelski, especially if recent history is any indication. Smith was injured the last time the teams played on March 31, but Marchessault and Karlsson played (at least) three more minutes against Donskoi, Kane, and Pavelski than any other San Jose forwards.
It will be interesting if those same matchups are used when the series shifts to SAP Center for Games 3, 4, and possibly 6. On March 22, the last Sharks-Golden Knights game in San Jose, Mikkel Boedker, Logan Couture, and Tomas Hertl drew Marchessault and Karlsson (Smith was hurt then, too) most of the game. Boedker, Couture, and Hertl functioned as San Jose's shutdown line in the first round, playing most of their minutes against Ryan Getzlaf and Rickard Rakell, who consistently remained on the Anaheim Ducks' top line.
No matter which Sharks line draws Karlsson, Marchessault, and Smith, it will need to improve on its first-round performance. San Jose's top-six forwards, who spent most of their time against Anaheim's top-two lines, were the team's six-worst forwards in terms of five-on-five corsi-for percentage (none eclipsed 43 percent), and only Couture was not outshot, according to Corsica Hockey. None of them were outscored five-on-five, but that was largely owed to the team's strong finishing ability and the outstanding play of Martin Jones in net.
Jones is a proven playoff performer, but the Sharks were unlikely to continue to score on nearly 12 percent of their five-on-five shots before factoring in the presence of Marc-Andre Fleury, the playoff leader in five-on-five save percentage, in the opposite crease. That's even less likely now. Plus, the Golden Knights are far more disciplined (plus-16 penalty differential in the regular season) than the Ducks (minus-60), so San Jose likely won't be able to mask any five-on-five mismatches with a strong power play.
Thus, it'll go a long way for the Sharks if their top-six forwards keep pace with Karlsson, Marchessault, and Smith. Getting the best of the matchup would go even further.