Robyn Regehr is "likely" to make his much anticipated return to the Kings lineup for game 2. Regehr received medical clearance to play game 1, but the Kings decided to take advantage of the two-day break between games 1 and 2 give him more time to recover. He had suffered a knee injury courtesy of notorious goon Teemu Selanne (edit: actually on an earlier hit by even more notorious goon Devante Smith-Pelly, my bad) and missed the past 14 games.
Longtime followers of Jewels From the Crown will know that this is not exactly a Robyn Regehr fansite. Even the most ardent Regehr admirer would concede that he has minimal offensive ability and is at best a one-dimensional player. But there were worrying signs that he might not even be an effective shutdown defenseman. His possession numbers in Buffalo were atrocious, even when adjusted for tough minutes and a bad team. His unadjusted possession numbers improved upon arrival in LA, as he was suddenly surrounded by teammates who were good at hockey, but he continued to be a massive drag on his team's possession numbers.
In 2013-14 the Kings abandoned the Doughty-Regehr pairing and moved Regehr to the second pairing with Voynov. The good news is that despite the demotion, Regehr was better this year. Really, he was! Look at the charts (all data regular season only, and from stats.hockeyanalysis.com):
Regehr WOWY, 2012-13
|Doughty with Regehr||186||51.5%|
|Doughty without Regehr||759||59.1%|
Regehr WOWY, 2013-14
|Doughty with Regehr||302||54.7%|
|Doughty without Regehr||1087||59.3%|
|Voynov with Regehr||776||53.0%|
|Voynov without Regehr||577||57.7%|
Regehr-Voynov was not a thing until this year, but the success of Regehr-Doughty both years is a pretty good clue as to how Regehr is doing. The Kings were pretty much the same possession team this year and last so there's no need to adjust for team quality. As always, though, WOWYs must be put in the context of deployment.
In both years, Doughty is mostly with Muzzin when not with Regehr, and is probably playing somewhat tougher minutes with Regehr than without him, especially with regard to zone starts. But zone starts alone can't account for such a dramatic reduction in Doughty's possession numbers. Doughty-Muzzin was/is still playing the toughest competition, and the gap in Corsi% both years is enormous. Regehr-Doughty just didn't work at all.
As for Voynov, when he wasn't with Regehr this year he was mostly with Mitchell (55.7% in 424 minutes) or Muzzin (66.8% in 116 minutes). Voynov-Muzzin were almost certainly sheltered together so take those results with a grain of salt. Voynov-Mitchell probably received very similar minutes to Voynov-Regehr though, so there's some evidence that Mitchell is a better fit on the second pairing.
Regehr's numbers do show some improvement. A 53% with Voynov isn't great (remember, the Kings as a whole are a 56.8% team), but it's a heck of a lot better than a 51.5% with Doughty. The year-to-year Doughty numbers offer an even clearer comparison. Regehr's still a possession drag, but he has gotten better.
Regehr is likely to return to the second pairing with Voynov, pushing Mitchell to the third pairing and Matt Greene out of the lineup entirely. Given the data above, I do not think that is a wise decision. Voynov has a track record of doing better with Mitchell than with Regehr, so I can't see much reason to think this makes the second pairing better. Meanwhile, Greene has actually done quite nicely on the third pairing with Alec Martinez, albeit in soft minutes. After a decent regular season together (58.6%) the two have the best possession results of any LA pairing this postseason. Greene has not received many accolades for his recent play, but that's probably bad luck. Quick has posted a .885 5v5 SV% when Greene is on the ice, which makes the defenseman look much worse than he is. Greene's overall play has been solid.
If anything, looking at Regehr's 2013-14 possession numbers is a bit too generous. After all, those are presumably Regehr's results at something like normal effectiveness. Between any lingering effects of the knee injury and rust after a month without playing hockey, it's reasonable to guess that Regehr falls short of that standard in game 2. His improvement this year allows some hope that his return won't be a disaster. Still, this decision creates a lot of risk with very little potential benefit to compensate.