A really good line can start clicking for a number of reasons.
Sometimes, it's simply due to the individual talent of the three forwards in question, but it isn't always that easy. Putting the best three players together doesn't always pay dividends. Often, it's more effective to combine ones whose strengths complement each other perfectly.
The top two units in hockey clearly play in Denver and Boston. However, the rest of the list isn't as cut-and-dried.
Some lines - like those featuring both Connor McDavid and Leon Draisaitl - were more than effective but weren't deployed consistently enough to qualify, while others (like those consisting of McDavid and various other teammates or the ones featuring Hart Trophy winner Nikita Kucherov) were certainly productive, but didn't rank highly enough in many of the relevant analytic categories.
Here's who we consider the NHL's five most consistent all-around three-man units based on advanced stats from the 2018-19 regular season, their collective two-way talent, and the success of their respective teams.
All stats are at five-on-five. Games played denotes number of contests played together as a line. League ranking is in parentheses. Time-on-ice ranking is based on a minimum 400 minutes at five-on-five.
The Vegas Golden Knights' unit of Jonathan Marchessault, William Karlsson, and Reilly Smith wasn't the powerhouse this past season that it was two years ago. However, it remained one of the NHL's most dependable lines.
While other productive groups like the Dallas Stars' top line of Jamie Benn, Tyler Seguin, and Alexander Radulov produced a better share of Goals For in 2018-19, the enduring Golden Knights line played more together than all but one three-man forward unit in the NHL, driving possession at a favorable rate in the process.
They skated about 340 more minutes together in total than their Stars counterparts, who were shuffled around at times.
That heavy deployment was a testament to the chemistry that this Golden Knights line has demonstrated for the better part of two seasons, and if their Expected Goals For percentage is any indication, it's likely to stay that way.
This was an impressive trio in 2018-19, and it was only slightly less effective than the third-best group on this list.
The Calgary Flames' triumvirate of Johnny Gaudreau, Sean Monahan, and Elias Lindholm consistently drove possession and ranked relatively high in many analytics categories while leading a team that boasted the NHL's third-best offense.
This unit also posted respectable Scoring Chances For (52.56), High-Danger Corsi For (52.65), and High-Danger Goals For (58.82) percentages.
What this line did in 2018-19 definitely deserves some recognition, particularly when you remember it was Lindholm's first season with the club.
No line scored more goals at five-on-five in 2018-19 than the 53 buried by the Zach Hyman-John Tavares-Mitch Marner unit.
Only the No. 1 line on this list and the Golden Knights' top unit played more together during the campaign than this Toronto Maple Leafs trio, which posted a Scoring Chances For percentage of 56.51, exceeding the aforementioned Flames line in the process.