When the Eastern Conference Finals start on Friday, the Lightning will be facing their strongest competition thus far in the playoffs. Over the last quarter of the season, the Pittsburgh Penguins have been a juggernaut. By almost every statistical measure, the Penguins have been one of the best teams in the league.
The following two charts show the Lightning and Penguins' rankings in shot metrics and scoring chances for the full season and for the last 20 games of the regular season plus the playoffs. The story they tell is obvious.
Over the last quarter of the season and into the playoffs, the Penguins rank in the top 5 in every metric except shots against and save percentage. In those two metrics, they rank 10th. The full season numbers don't paint Pittsburgh as quite so dominant. However, they started the season slowly before making a coaching change in November. After that change, they continuously improved their play through the winter and spring evolving into one of the most dangerous teams in the league by the end of the season.
The following graph from Emmanuel Perry's (@mannyelk) corsica.hockey reinforces that idea. It shows the 25 game rolling average of the Lightning's and Penguins' expected goals percentage for the whole season including the playoffs. The improvement in Pittsburgh's play is evident from December through February and since that time, they have been one of the best teams in the league. They are currently first in expected goals percentage for the year including the playoffs at 55.29%. The Lightning rank a respectable 8th at 51.97%.
The numbers are pretty clear going into this series. The Lightning are underdogs by almost any quantitative measure. Micah Blake Mccurdy's (@ineffecitivemath) model has the Pens at 64% to win the series. Matt Cane's (@Cane_Matt) model has the Penguins at 62%. Dom Luszczyszyn (@omgitsdomi) compiles several statistical models including the two mentioned above into one. That model also has the Pens at 62%.
Not only have the Penguins been playing better by most measures but they will also have home ice advantage in the series. And barring a miraculous return by Steven Stamkos, the Penguins are also the healthier team. None of this means the series result is a foregone conclusion. But it does mean the Lightning will need to play their best and probably get some luck if they hope to return to the Stanley Cup Final.
All numbers in the article are 5v5 score and venue adjusted. The numbers for the first two charts come from war-on-ice. A glossary for those statistics can be found here. The the last chart comes from corsica.hockey. An explanation of the expected goals statistic can be found here.