The Stanley Cup playoffs had some lopsided matchups in the opening round, but all four second-round series are so well-matched that one lineup decision could be enough to tilt them in one direction or another.
Whether it's the choice of injury replacements, depth players, the deployment of the special teams or which goalie to start, here is one key lineup decision each team is faced with in the second round.
Nashville Predators
Having a lot of forward depth gives the Predators resilience against injuries and suspensions, but it also makes for difficult decisions when everybody is available.
As it stands, Mike Fisher will most certainly center Nashville's fourth line, but there are some interesting choices about who should play on his wings. At the start of the first-round series with the Colorado Avalanche, Fisher played with Ryan Hartman and Miikka Salomaki. Once healthy, Calle Jarnkrok replaced Salomaki in the lineup, and veteran Scott Hartnell stepped in when Hartman was suspended for Game 6.
All four wingers are available for Game 1 against the Jets, as is prominent rookie Eeli Tolvanen, who played just three games with the team after spending the season with Jokerit Helsinki in the KHL. For that matter, the Predators also have Frederick Gaudreau, Harry Zolnierczyk and Brandon Bollig at their disposal.
According to each player's scoring rate, and the player's impact on the team's share of shot attempts, the best combination would be for Hartnell and Hartman to flank Fisher on the fourth line, although a case could also be made to for Jarnkrok.
Winnipeg Jets
Toby Enstrom missed the final eight games of the season and the entirety of Winnipeg's first-round series with the Minnesota Wild with a lower-body injury. His imminent return at some point of the team's second-round series with the Predators will lead to an interesting choice about who should be dropped from the lineup and with whom Enstrom should play.
Since he played all but two of his 43 games with Dustin Byfuglien this season, it makes sense to reunite the two, and to scratch Joe Morrow. However, an argument can also be made to drop Morrow to the third pair and replace Ben Chiarot as the partner for Tyler Myers.
If we're judging these players by their performance in the first round, then Chiarot has earned the opportunity to keep his spot. His 22 hits ranked second on the team to Byfuglien (25), he was a regular on the penalty kill (1:50 per game), and he drew a team-high three penalties.
San Jose Sharks
In San Jose's case, most of the interesting lineup decisions have already been made. As demonstrated by the Sharks' four-game sweep of the Anaheim Ducks, they worked out perfectly and are unlikely to be reversed for the second round.
While Paul Martin's reinsertion into the lineup on March 17 was certainly interesting, the more recent decision was the makeup of the fourth line. Rather than turn to veterans like Jannik Hansen and Joel Ward, the Sharks opted for rookie Marcus Sorensen, journeyman trade deadline acquisition Eric Fehr and Melker Karlsson.
The results? The Sharks outscored Anaheim 4-0 with Sorensen on the ice, and held the edge 42-24 in shot attempts and 18-8 in shots, according to Natural Stat Trick. The Sharks will stick with what works to start the series, but after losing 7-0 in Game 1, they may make some tweaks.
Vegas Golden Knights
Though he normally plays on the second line with Erik Haula and James Neal, David Perron was placed on the third line with Cody Eakin and rookie Ryan Carpenter upon his return to the first round for Game 3. That choice was probably made in light of the fact that rookie Alex Tuch was playing effectively on the second line in his absence. Should that decision be revisited for the team's second-round series against the Sharks?
With a career-high (and team-leading) 50 assists this season, it can be argued that Perron is the team's hottest playmaker. Placing him on a line with two players who combined for 20 goals in 116 games this season seems like a wasted opportunity. The Golden Knights scored seven goals in Game 1, so keeping Perron with Eakin and Carpenter appears to be the short-term move. However, if the offense hits a rough patch, don't be surprised to see Perron moved back up.
Pittsburgh Penguins
Pittsburgh's regular-season team scoring leader Evgeni Malkin injured his leg in Game 5 of the team's first-round series against the Philadelphia Flyers and missed Game 6 -- a game in which his usual linemate Carl Hagelin was also injured.
Malkin and Hagelin both missed Game 1 of Pittsburgh's second-round series against the Capitals, so the team went with Riley Sheahan and Dominik Simon with Phil Kessel at even strength. If Malkin misses more time, the Penguins will have to decide whether they like that array going forward as well as make a decision on how to best operate the power play.
Throughout the regular season and the playoffs, Pittsburgh has relied heavily on its four-forward power-play deployment of Malkin, Sidney Crosby, Patric Hornqvist and Kessel. Each player averaged at least 3:32 per game on the power play in the regular season and 5:14 in the first round of the playoffs, while no other forward on the team averaged more than Jake Guentzel's 1:46 in the regular season and 2:28 in the first round.
The default option might have been to play two defensemen on the top unit, Kris Letang and Justin Schultz. During the past three seasons, Letang has averaged 5.44 points per 60 minutes on the power play, and Schultz has averaged 4.61. The other alternative -- and the one they used in Game 1 -- is using Guentzel on the top unit, as he has averaged 4.51 points per 60 power-play minutes, and to have Kessel drop back to Malkin's position on the point.
If Malkin remains out in Game 2 and beyond, will the Penguins stick with these new combos or try something new? We can't argue with the ultimate result, as the team won 3-2, but the top line of Crosby, Hornqvist and Guentzel did all the scoring (and they went 0-for-2 on the power play).
Washington Capitals
Washington's most interesting lineup decision came in Game 2 of the first-round series with the Columbus Blue Jackets, when Andre Burakovsky was knocked out of the lineup with an upper-body injury.
Recently, Burakovsky was playing on a versatile two-way line with Nicklas Backstrom and T.J. Oshie. The Capitals briefly replaced him with rookie Jakub Vrana, before turning to another rookie, Chandler Stephenson, for the balance of the series.
In their second-round series against the Penguins, the Capitals may want to consider placing Alex Ovechkin on that line instead at some point (though they stuck with the same lineup in Game 1). For the tail end of the season and all of the first round, Ovechkin has been playing on the top scoring line with Evgeny Kuznetsov and Tom Wilson. While it normally makes sense for the Great Eight to play on a scoring-focused line, the following player usage chart from Hockey Abstract suggests that an alternative deployment may prove superior.
Those who take on top opponents are near the top of the chart, and Ovechkin ranks third from the top, behind Backstrom and Oshie. Vrana is below average, and Stephenson typically plays only against depth lines, making them less suitable for deployment on the top two-way line.
Devante Smith-Pelly is more accustomed to a two-way role than these other options, but the color of his circle indicates that the team doesn't do as well when he's on the ice, from a shot-based perspective. So it would be best to keep him on the depth lines, perhaps with Stephenson.
Offensively, those who play more often in the attacking zone are toward the right. And yes, that includes Ovechkin, but not to the same extent as Vrana, who could play with Kuznetsov and Wilson until Burakovsky's return.
Tampa Bay Lightning
The Lightning are among the pioneers who have been experimenting with the idea of playing seven defensemen and 11 forwards, instead of the usual six and 12. That gives a team added flexibility later in the game, especially if one of its defensemen gets injured, is penalized or is playing poorly.
In their first-round series against the New Jersey Devils, the Lightning went with six defensemen: Victor Hedman and Dan Girardi, Anton Stralman and Ryan McDonagh, and Braydon Coburn with rookie Mikhail Sergachev. For their second-round series with the Bruins, they may want to consider adding Jake Dotchin to the mix.
In Dotchin's 83 career games, the Lightning have outshot their opponents 1,300-1,183 with him on the ice, for a Corsi differential of plus-117. In percentage terms, their share of shot attempts has improved from 51.18 to 52.36 percent for a relative Corsi percentage of plus-1.2 percent. He also adds a physical element, with 2.2 hits per game, which ranks first among Lightning defensemen during the past two seasons.
Adding Dotchin would mean scratching one of the team's fourth-line forwards. If Ryan Callahan is less than 100 percent, this becomes an easier decision. In his absence, Cory Conacher has played just 10:09 in two games combined. Otherwise, the odd man out would be Chris Kunitz, who is 38 and averaged 7:59 per game in the first round.
Boston Bruins
In addition to the headline-grabbing trade for Rick Nash, the Bruins added plenty of depth late in the season, including forwards Brian Gionta and Tommy Wingels, rookie Ryan Donato and defenseman Nick Holden. Should one or more of these players be in the lineup?
Gionta would provide a lot of experience and versatility. His 112 games of playoff experience ranks second to Zdeno Chara, with 154, and he won the Stanley Cup with the Devils in 2002-03. His best days are behind him, but Gionta is a versatile player who can kill penalties, backfill the power play, play tight defensive hockey and provide secondary scoring.
Wingels adds physicality, but it comes at a price. He has thrown 1,212 hits in his career, which ranks 20th among active forwards since 2010-11, but his teams' share of 5-on-5 shot attempts has dropped from 52.7 to 49.9 percent with him on the ice, for a relative Corsi percentage of minus-2.74 percent. Unless the series gets particularly rough, he might remain in the press box.
Offensively, Donato would be the most exciting addition. After scoring 26 goals in 29 games for the Harvard Crimson -- and leading Team USA at the Olympics with five goals -- Donato scored nine points in 12 games down the stretch, playing mostly with David Krejci. That infusion of scoring would make the most sense at home, where Boston can use the last line change to get the right matchup.
On the defensive side, Holden would provide assistance. For five seasons, Holden has capably served as a defensive-minded No. 4 option at even strength and on the penalty kill for the Colorado Avalanche and the New York Rangers. In that time, he ranks 12th among defensemen with 791 hits, has averaged 1:56 per game killing penalties, and his offensive zone-start percentage of 44.79 percent is 18th lowest among active defensemen who have played at least 100 games, so he gets the job done even when facing tough assignments.