One of the problems with analyzing minor-league stats is the quality of competition. You could have a "fifth-liner" who's great against AHL players but can't hack it in the NHL. The same problem exists with goalies, who can put up great numbers against these fifth- and sixth-liners, skaters who aren't good enough to play a level higher. This varying level of talent in the minors makes it harder to figure out whether that .920 or .930 save percentage actually means anything for that goaltender's potential NHL career.

Of course, we have NHL equivalencies we can use to estimate how an AHL (or CHL, etc.) performance would project to the NHL, but we can actually go a little bit farther than that and try to evaluate these AHL goalies against NHL competition directly.

SETUP

Not every AHL player is the same. The shots a goalie faces in the minors could include some taken by skaters who are good enough to be in the NHL. Those shots may be more useful when trying to figure out how this goaltender will perform against a full team of NHL players. To take an example from baseball, you can evaluate college players to some extent by looking only at their results when they pitch to or bat against players who were drafted by MLB teams. The logic being, "the performances players post against their fellow future professionals should have some predictive value."

We can do this for hockey too. While not as extensive as their NHL cousins, AHL statistics still track shots by every skater in every game, allowing us to figure out every goaltender's save percentage on shots taken by each skater over the course of the year. We can then divide those shooters into two groups: those who played in the NHL that year and those who did not. We're left with a few hundred "NHL shots" faced by the average AHL goalie, not enough to draw any conclusions unfortunately, but maybe enough to make us take a closer look at players who could have been undervalued before.

Couple of technical notes: I looked at all AHL games, season and playoffs, but threw out any games where the opposing team used two goalies. (In those cases there's no way to tell which goalie faced which shots from the AHL boxscore.) An "NHLer" is defined to be anyone who appeared, however briefly, in the NHL in 2011-12 -- or, rather, anyone with the same name as someone who did. (And I could have missed some players who went by Michael in one league and Mike in the other, for example).

Shots can be attributed to the wrong player or miscounted entirely by the in-house scorekeeper, so there may be additional hidden inaccuracies here. And future versions of this analysis will remove empty-net goals, which shouldn't be in here but are hopefully rare and random enough that they don't unfairly penalize anyone.

RESULTS

The top 10 goaltenders by "save percentage against NHLers" (at least 300 shots faced) are:

Name               Team        Shots    Sv%  Age
Eddie Läck         Chicago       529   .922   23
Jeff Zatkoff       Manchester    390   .921   24
Michael Leighton   Adirondack    552   .920   30
Jacob Markstrom    San Antonio   403   .918   21 
Dustin Tokarski    Norfolk       475   .918   22
Cedrick Desjardins Lake Erie     326   .917   26
Cameron Talbot     Connecticut   468   .917   24
Robin Lehner       Binghamton    375   .915   20
Danny Taylor       ABB/SPR       527   .915   25
Kevin Poulin       Bridgeport    521   .912   21

(Age is as of Dec. 31, 2011)

DISCUSSION

The average save percentage for all AHL goalies was just .894, so all of these players saved their team several goals simply by performing better than average against NHL callups. (The average save percentage against non-NHLers was .917, which isn't that suprising of a difference since lucky shooters are probably more likely to be called up.)

Aside from his age, Läck's performance is particularly impressive given that he faced more shots from NHLers than all but six AHL goaltenders overall, and more than eight of the nine other players on this list. We can run the risk of taking this too far, obviously -- 529 shots is the equivalent of only about 15 to 18 games -- but if you're looking to argue in favour of his NHL readiness, a .922 is certainly better to see than an .892.

Zatkoff offers an interesting study in contrasts here. His regular-season save percentage was .919, basically the same as his teammate Martin Jones, but against NHLers Zatkoff put up a .921 and Jones (who is three years younger) was near the bottom of the list with an .885. Not a large enough sample to throw cold water on Jones' performance, but enough to make you look twice. I bet that if you ask the Kings about both players, you'd get an answer along those lines even if they don't have the exact numbers.

I'll spare you the list of the bottom 10, because it's not that interesting, but the worst performance was probably Tom McCollum, who had an .849 save percentage in 325 shots faced. (This is a good time to remind you that friends don't let friends draft goaltenders in the first round.) Other players who got to pad their numbers against lesser competition in '11-12 include Eddie Pasquale (.870 against NHLers, .936 against the rest), Mike McKenna (.883, .924), and old Toronto favourite Joey MacDonald (.885, .942). Not that anyone confused them with NHL-quality goalies before today.

Anyway, there's not much we can conclude from one year of data, other than identifying who might perform better in the NHL in the next few years, all else being equal. Young players like Markstrom or Tokarski were already thought highly of, presumably, by their respective organizations, but the analysis here might give more reason to be optimistic about their futures.