Frank Corrado and Martin Marincin are the two Leafs defencemen about whom we have the least information. They have both been in and out of the lineup all year, though Marincin has seen more games on the whole. Corrado, famously, was claimed from the Canucks off waivers earlier this year, and promptly sat the next 41524 Leafs games as a healthy scratch (or so it seemed).
However, in the last few weeks, both Corrado and Marincin have seen themselves in the lineup more often than not, and in the wake of the Dion Phaneuf trade, that looks likely to continue for the rest of this season. As has been said by many people, this year is about two things for the Leafs: getting a good draft pick, and getting certainty over which players will have a role to play on the next good Leafs team. The former is all but guaranteed at this point - the only question is whether we'll get lucky (and get a superstar prospect) or unlucky (and get a merely 'good' prospect). The latter is something that still needs to be done.
This year, we've learned that the Leafs two best players, Nazem Kadri and Jake Gardiner, are really, really good, and should be prized. We've learned that Morgan Rielly is an all-offense, no-defense glass cannon (who becomes mediocre offensively when shackled to Matt Hunwick). But we haven't learned much about the guys below them, including the aforementioned Marincin and Corrado. That should change now.
There are some signs of hope regarding the two young defencemen, particularly when paired together. We can see from Frank Corrado's spider chart (courtesy of HockeyViz.com) below that when paired with Marincin, the two are defensively stingy and destructive offensively, to the tune of a Score Adjusted Corsi For % of ~65%.
Now, the major caveat here is that this is in 34 minutes of action, which is a ludicrously small sample. It comes almost entirely from four recent games worth of data (the Flames, Oilers, Canucks, and Blackhawks games). Aside from the Blackhawks, that's not a murderers row of teams. That being said, there are reasons to think this would work in a larger sample size.
Corrado and Marincin have put up some truly stellar possession results in their young careers, including this year. Almost every Leafs defenseman is notably worse away from Corrado/Marincin than Corrado/Marincin are from them. And it's not like they've been carried by any other Leafs player - both have played mostly with the 4th and 2nd lines of the Leafs (no outstanding possession drivers on either line) and they haven't played with Gardiner either (our best defenseman). Of course, there are very small samples behind each of these, so I'd be hesitant to make any conclusions besides 'this is a good sign, and we should give them more minutes to see if this pattern persists'.
Now, of course, there are caveats here. Corrado and Marincin have started more shifts in the offensive zone (proportionally) than any other Leafs defensmen. That being said, given what we know about the muted impact of zone starts outside the very extreme cases, and the fact that their results are so good from a possession perspective (both together and apart, with any Leafs defenseman), I'd be willing to bet that even in tougher minutes, they'd continue their success. To me, it's more likely that their zone starts are a consequence of their excellent possession play, rather than the other way around.
You may have noticed that I've only really discussed possession here, and not individual scoring. The reason for that is because more and more, I'm realizing that I don't care about individual scoring, especially not for defensmen. Players who move the puck in the right direction are valuable, because that leads to goals. Whether they're the ones on the scoresheet or not isn't of utmost importance if they continue to generate those chances and suppress those of the opposition. The reason we care about points in general is because they're indicative of players who are getting a lot of chances and scoring a lot of goals (and in particular, scoring more than their opponents are). But if a player is consistently driving excellent possession results and is outshooting their opposition, what does it matter if they aren't the one who puts it in?
I find that many people's impression of these two players is coloured negatively by their lack of point totals. My view is, it doesn't matter. When they're on the ice, the Leafs dominate possession. Teams that dominate possession tend to dominate goals. While that latter step hasn't happened yet for Corrado and Marincin, years and years of research indicate that it should. Also of note is that both Corrado and Marincin have had pretty awful puck luck this year (unless you think they're doing something unique when on the ice to reduce their on-ice S% at 5v5 to less than 6%) - a few more bounces and they have respectable points tallies as opposed to terrible ones, and we all feel better about their level of play.
In their limited time on the ice, these two have made everyone better, and have dominated when put on the ice together. I think it would be smart to give them more of a chance to prove that these results aren't just a blip, but are representative of their true abilities. Particularly as players on the blueline (like Polak) continue to be moved out, Corrado and Marincin should get a bigger role, and if their excellent results persist, then the Leafs might have found two top-end defensemen for nothing.
Note: All stats are 5v5 unless otherwise noted. Stats are current as of Feb 20th, and don't reflect the Philadelphia game.