Aside from the occasional shake up of the fourth line and some minor switching of the top 9, Hitchcock has been using 4 lines consistently during the playoffs.
Schwartz - Lehtera - Tarasenko
Fabbri - Statsny - Brouwer
Berglund - Backes - Steen
Reaves/Ott/Jaskin - Brodziak - Upshall
These lines have accounted for most of the ice time seen by any line combinations during the course of the playoff season. To try to understand how these lines have been so successful in the playoffs, I compared them to the regular season. First off, the top of the dataviz below shows you the 5v5 time on ice they have seen during both the playoffs and regular season. Vladimir Tarasenko's line has seen the most 5v5 ice during both the regular season and the playoffs. This sounds about right. In fact, most of the ice time shakes out the way we would expect. One exception is David Backes' line. The Backes line has seen about as much ice time in the playoffs as it did during the regular season (roughly 80 minutes).
Let's focus in on the Backes line real quick. Possession wise during the regular season this line was right around 50% which was also the average for all lines during the regular season (orange bars and orange reference lines). Their shot attempt generation was below the team lines' average for the regular season. Their goals for percentage for the regular season is right at 50%. However, their on ice shooting percentage was well about the team lines' average for the regular season. So very mediocre possession but when it came to scoring this line was able to finish its chances. How does this compare to their playoff numbers? Backes line's possession during the playoffs has been below the team's average in both the playoffs and regular season. Their goals for is not a joke. They are currently at 100% goals at 5v5 during the playoffs. To put that another way, the line of Backes, Berglund, and Steen have not been on the ice together for a goal against during 5v5 play so far during the playoffs. Is this sustainable? Probably not, especially considering they are sub 50% in possession. This is what I would call the Brian Elliott Effect. Elliott has been playing so hard this playoffs that he has been able to cover for his teammate's defensive mistakes. He has also been able to handle the quantity of shots the Blues have faced during the course of the past 14 games. If the Backes line has the opportunity to generate more shot attempts in the Shark's zone, this could not only help Elliott, but it would provide some confidence that they can maintain their shooting percentage and goals for percentage.
The real star of the past 14 games has been the FSB line of Fabbri, Stastny, and Brouwer. Their corsi for is below 50% but 2nd best line on the team during the playoffs. Their corsi for per 60 exceeds the team's average for both the regular season and playoffs. But the real story is their goal scoring prowess. Their on ice shooting percentage is almost 12% for the playoffs. It is the highest on the team. Their goals for percentage is 72% and second highest on the team. Is this sustainable? For the short term, maybe. Depends on how Hitchcock matches them up against the Sharks. Long term? Probably not. But considering there are at most 14 games left in this season, it would not be unreasonable to assume they continue scoring goals even if it is not as often as the previous series.
The Tarasenko line was almost non-existent during the 2nd round against Dallas. Yet, this line was able to maintain its possession numbers above 50% and generate shot attempts at a rate higher than any other Blues line has been able to so far during the playoffs. If this continues, the Tarasenko line will start scoring again and they will be a factor in the conference finals. Otherwise, if teams continue to focus all their energies on the Tarasenko line, then this will continue to give the Backes' and FSB line the space they need to continue scoring goals and winning games for the Blues. One last bit of information about the Tarasenko line. When we take a look at the average number of shot attempts it takes a line before they score a goal, during the regular season Tarasenko's line had the lowest needed out of the four lines we are currently looking at for this article. They scored a goal for every 17 shot attempts they took during 5v5. However, during the playoffs this year, their line has the most out of all the four lines with 38 shot attempts per goal scored. It could be that Tarasenko's line is being forced to take bad shots from bad locations. But even then, volume of shots is key, so if they can keep up the rate of attempts, they will see success in this upcoming series -- regardless of their match up.
Which brings us to the PDO momentum chart. If you remember these charts from earlier in the season, I am using what they call a MACD analysis. The orange line is an 8 game moving average of the team's PDO and the blue line is the 20 game moving average. The light gray line is the PDO per game for each team. Even though the lines are small, it is easy to see that each team is roughly at the same point with PDO in regards to the 8 and 20 game moving average. The only difference is the Blues started right at 100 at the start of the playoffs and have grown their PDO since then. San Jose was past the 100 mark for PDO and has managed to maintain it throughout its run. This series might all come down to whose "puck luck" runs out first?