In one of the recent comment threads, an imromptu discussion about Milbury vs. Snow popped up, with goaltending a featured sub-thread.  To wit, the bold assertion of metalstar:

As it stands right now DP and Luongo are equal.

Luongo has proved to be nothing more than a work horse regular season goalie who can’t get it done in the playoffs. Vancouver has fared no better in the in post season with Luongo than they did without him. DP when he was fully healthy and in top form was a major reason why the Isles made the playoffs the last couple of times they managed to get there.

Talk about serendipity - the Contrarian Goaltender talks about Luongo's playoffs in a recent post, to which I now refer the curious.  I will go over some different numbers below the jump, comparing more apples to apples regarding Luongo and DiPietro - their formative goalkeeping years behind similarly-struggling teams.

Here's some stat-fu for everyone to consider.  The numbers are for each goalkeeper in their age 21-26 seasons, with DiPietro's numbers not including his post All-Star Game work, after he had first been injured:

Those numbers for Luongo happen to coincide with the five seasons he spent as a Florida Panther.  The GAA for both is negligible over the same age range, and Robby's got Rick by a significant amount in saves percentage.  He has twice as many shutouts in only 38% more games.  The record is the only thing that's worse - and when we look, we see that the difference is offense, not defense or goalkeeping:

The Isles gave their keepers much more support than the Panthers, on balance; their failings were in goal prevention.  The team had better-than-average offense three times, but even when outscoring their opponents, they never had better-than-average goal prevention. (Being only 1 and 2 goals better than the league average over 82 games is negligible.)  Florida never had an above-average season - in fact, their offense was bottom-third of the league every year.  Of course, they were also below-average in stopping shots, as per above - but how much was Luongo and how much the defense?  A suggested answer lies further down.

Luongo also outperformed his backups by a great margin, as compared to RDP, over the same time period.

Dig that last number.  It suggests why the Panthers were worse-than-average in the goals permitted department, despite Luongo's strong play - Florida's matador defense.  Essentially, Lou faced four more shots per game than Rick, and stopped all of them. (¡Olé!)  He also faced more shots per than his backups, while the Isles were essentially the same team in front of everyone for those years.  Rick was still better than Snow and Dubie (and others) but not by nearly as much as Lou was better than... well, Trevor Kidd and Jani Hurme, but still!

Season-per-season it's much the same.  Luongo had three seasons where he was tremendously better than his backups (01, 02, 04), one where he was decently better (03), and in 06 he was marginally better.  Since in '04 and '06 his backups played so much less than he did (he led the league with 75 games in '06, for example), it's just as likely that luck played a big part in those short-term performances: Steve Sheilds was just bad in '04 behind an incredible year for Bobby Lu, while in '06 Jamie McLennan had good results behind an average year for Luongo.

In DiPietro's case, he also had three seasons where he was much better than his backups (04, 06, 07), and one where he was decently better (08, pre-injury).  In '03, he WAS the backup behind Chris Osgood and then Garth Snow, and was a fair sight worse, albeit in just ten games.

Given that Luongo had already climbed to elite status while in Florida, one would expect more success with the stronger team in Vancouver.  Again, the Contrarian Goaltender is on that case.  In brief, Luongo has sparkling results in international play, and in the playoffs, the only team he's been bad against is Chicago, losing both his series against them.  (The Hawks did just win a Stanley Cup - can you necessarily blame Luongo for not doing that well?)  The jury is still out about whether (or how much) Roberto Luongo is responsible for Vancouver's recent playoff history - but I think we can safely return a verdict on Metalstar's charge, that at this point he is no better than DiPietro.  That verdict is, he is better by a significant margin... he was better at the same age, he was better before RDP's injuries, and he is certainly better now.