Anton Stralman is widely considered one of the best defensemen in the NHL. His contract is often cited as one of the smartest free agent signings by any team in the past several years. He and Victor Hedman combine to form an elite defensive pairing that is fundamental to the Lightning's success over the past two seasons. When Stralman suffered a broken fibula on March 25th, the Lightning lost an irreplaceable player.

Over the past two seasons, he is seventh among defensemen with at least 200 minutes of time on ice (TOI) in corsi for percentage (CF%) and eighth in corsi against (CA). The Lightning are a strong shot suppression team when he is on the ice and most importantly, he is third in on-ice expected goals for percentage (xGF%). He is a prototypical top pairing defenseman for today's NHL and when paired with Hedman, the two form a devastating combination.

Losing Stralman was a major blow to the Lightning's chances at making a deep playoff run. When the injury occurred, the unofficial timetable for his return was 4-6 weeks. With the Bolts likely to start their second round playoff series against the Islanders on Thursday, that would put Stralman one day short of five weeks since the injury. While the team hasn't said anything officially, indications are that he is likely to make his return at some point during the second round. What does that mean for the Lightning? A lot. A whole lot.

To start, this set of charts looks at the overall stats for the Lightning's entire season (including playoffs) in terms of shot generation and shot suppression before and after the Stralman injury. The top two charts show both shots-for and shots-against. The lighter shade of blue shows how much the Lightning are outshooting their opposition. The chart on the left is the full season while the one on the right shows only March and April to focus more on when the injury occurred. After the injury, the shot generation numbers hold similar to where they had been prior to the injury. However, the Bolts have steadily been giving up more shots against since March 25. That's to be expected given that Stralman has elite shot suppression numbers. The bottom graph in this section shows the percentage of shots that are for the Lightning as opposed to the opposition. Again, the trend shows that after the injury, the Lightning have been generating a lower percentage of the shots overall. And based on the charts above, that is due to the decrease in shot suppression.

The team effects are what one would expect. Stralman is an elite shot suppressor. If he gets hurt, the most logical effect would be an increase in shots against and that's exactly what has happened. In addition to the team effects, one player has been effected disproportionately to the others. Victor Hedman is without his fellow Swedefender and while he is still one of the best defensemen in the league, Hedman doesn't have the same impact without a partner who thinks and plays the game at the same speed he does.

After the injury, Lightning head coach Jon Cooper tried a couple of different partners for Hedman before settling on Matt Carle. The frequent scapegoat for the Lightning's troubles had been consistently healthy scratched earlier in the regular season but had been playing better before the Stralman injury. While Carle probably takes more blame than he deserves, no one would reasonably suggest that he is a top pairing defenseman at this point in his career.

Cooper's decision making process is obviously unknowable. Maybe he trusted Hedman to cover for any mistakes that Carle might make. Maybe he trusted Carle's veteran experience ahead of anyone else to fill in on the top pair during time without Stralman. Whatever the reason, the results have been telling. The Lightning made it through the first round but Hedman and Carle are a much different top pairing than Hedman and Stralman.

The top chart shows all defensive pairs with at least 100 minutes of TOI together including the regular season and playoffs. The best pairs are in the top right quadrant while the ones that struggle most will are in the bottom left. Being in the top right indicates high shot generation and high shot suppression. Being in the bottom left indicates low shot generation and low shot suppression. The size of the bubble indicates TOI and the color indicates xGF%. As would be expected, Stralman and Hedman combine to form one of the best pairs in the league and the difference between that combination and the Lightning's current top pairing is obvious. While Hedman and Carle still do a solid job of generating shots, they don't perform nearly as well in shot suppression. Again, highlighting Stralman's unique ability in that area. The bottom chart tells a similar story. The drop off in shot suppression is huge when Carle fills in for Stralman. And even more concerning, the xGF% percentage plummets from nearly 60% to under 40%.

The numbers speak clearly. The Lightning are not as good defensively without Stralman and the impact is not small. It effects the team as a whole and particularly his partner Victor Hedman. But with Stralman seemingly set to return at some point in the second round, the Lightning are going to be a better team than they were in the first round. The question is whether he will return soon enough and how close he will be to his normal level of play. With Steven Stamkos still injured, the Lightning are already not operating a full capacity on offense. Getting back close to full capacity on defense would be a huge step toward being able to survive and advance to the conference finals for a second consecutive year.

All numbers for this post are 5v5 score and venue adjusted from corsica.hockey. A glossary for all of the statistics used can be found here.