I looked at MTL's scoring chances with either on the ice at 5v4, 5v5, and 4v5. Like the data at behindthenet.ca, this includes empty-net situations (e.g. 6v5 is counted as 5v5).
Link to my spreadsheet. For the 5v5 scoring chance WOWYs, I included only players with at least 50 chances with Hamrlik/Halpern. The dataset for scoring chances is unfortunately about only half as big as that of Corsi.
I'll assume that the Habs' TOI distribution on special teams stayed constant throughout the season, since I only have data until the end of winter.
Per the data, the Canadiens had 171 5-on-4 scoring chances for, 212 4-on-5 scoring chances against. Hamrlik was +79, -73, while Halpern was +2, -80. Per BtN, the Habs spent 443.7 mins at 5v4, meaning they averaged a scoring chance every 2.59 minutes. They spent 518.7 mins at 4v5 (the most in the league), which means a scoring chance against every 2.45 minutes. Again, this is full-season: it's not the Habs' true rate (which was higher, as they gave up that many chances over 3/4 of the season), but the comparison between Hamrlik's rate and the team rate should hold true if my assumption is correct.
Hamrlik clocks in with 201.45 minutes played at 5v4 (roughly), meaning the Canadiens with old #44 on the ice were creating chances at one every 2.55 minutes: a hair above average on that team. Halpern played only 9.36 minutes at 5v4, 4.68 minutes per chance, below average in small sample. He also played 165.6 minutes at 4v5, giving us 2.07 minutes per chance against. Competition and zone start don't exactly give him an excuse for such poor numbers compared to his team (though in a small sample they aren't that reliable; aside: Gionta with a 4v5 zone finish above 50% is spectacular). Hamrlik played 143.78 minutes at 4v5, at 1.97 minutes per chance. Above average. Looks like he'll be a legitimate option on the power play and can eat minutes on the Caps PK, given the team's rotation. I'm not so sure Halpern can take minutes on special teams, which means more PK time for the rest of the group in order to make up Gordon's PK time.
One more note on the PK--winning the draw may not be that important. If the coaches and management realize that, the PK shouldn't miss a beat without Gordon.
A reminder: "Delta1" is how much better the player is with Hamrlik/Halpern than without him, and "Delta2" is how much better Hamrlik/Halpern is with the player than without him. A very good player should have high positive Delta1s and low positive or low negative Delta2s.
Hamrlik looks like the real deal. That's not as much green as I would have liked, but some of the "big guns" on Montreal--Andrei Kostitsyn, Tomas Plekanec, and Jaroslav Spacek, the other players who Montreal's coaches prefer against the other squad's top line--saw better play with Hamrlik on the ice. Moreover, Hamrlik seems pretty consistent in his scoring chance ratios across the board (across, I'm guessing, a variety of situations: good/bad competition, good/bad zone start, and good/bad teammate support).
What I do find a little worrisome is that Hamrlik's scoring chance ratio drops precipitously without either of Montreal's top two lines on the ice, especially without Plekanec, Kostitsyn, and Gionta. What that suggests to me is that while Hamrlik is adequate in all zones, he's not able to drive the play at both ends of the ice like, say, Mike Green or Duncan Keith (or that he was really out of shape and/or overworked 3/4 of the way through the season). Then again, few defensemen are like that. Luckily, the Capitals have the personnel to both slot Hamrlik in a "Malhotra"-type role (out there in every defensive situation and rarely in an offensive situation, a role in which Hamrlik has proven himself very competent) and in a two-way role, in which he'll have a D partner who can play at both ends of the ice pretty decently (Green or Wideman).
Yikes. A downgrade from Boyd Gordon, almost certainly. That is an awful lot of red. Halpern a few years back was an extremely effective defensive forward, but this last year he was riding the percentages. At first look it seems like Halpern's play took a big step backwards between the 07-08 and 08-09 seasons, when he suffered a ruptured ACL at the World Championships. Players tend to take a few years to fully recover from serious knee injuries (see Brendan Morrison for another example), so there is hope that he may recover his previous form. I think it's unlikely, though. Fortunately, there are always plenty of Boyd Gordon-types available at the deadline for relatively little commitment in terms of assets to trade (Vancouver acquired Chris Higgins, one of the best "Boyd Gordon-types", for an AHL prospect-type defenseman and a 3rd round pick), contract term, and salary.
Here's what the Habs' (unofficial) scoring chance tracker had to say (in 140-character thoughts):
still haven't crunched the complete numbers, but... Hamrlik was in the red, somewhat overmatched (ctd)
Hamr basically had to play the toughs with Wisniewsky, who isn't very good in his own zone. If there is a soli minute eating...
(...) duo in front of him, he'll be fine. Still can contribute in all three zones in all three situations. Just needs some rest
Halpern is fragile (concussions) and outmatched in a tough-comp setup (the % favored him this year) but he's a solid FO guy
and was often sent as a RW with Plekanec in tough defensive assignments (ie less than 10 minutes in the game with a short lead)
and he did pretty good in those situations.
We'll see how this turns out. The Capitals' strong defense may compensate for not having strong center depth. Adding another defensive center would be nice, though, to free Backstrom from playing harder competition (his jump from bottom to middling and tough luck on the power play I felt contributed more to his struggles than an extra 5v5 defensive zone faceoff every 2 games and three lost 5v5 offensive zone faceoffs every four games, roughly, in 2010-2011 compared to 2009-2010). Nonetheless, I do feel safe in saying that this team is the strongest the Caps will ice (relative to the rest of the league) heading into the season of any year since pre-Jagr. With some good bounces come April and May...