People describe the 1999 Sabres that way but it isn't true. Buffalo was a good defensive team that lacked firepower. Yet, in the 1999 playoffs Buffalo's offence played above its head for three rounds. Buffalo averaged 3.33 goals per game in the first three rounds, well above league average, and never scored fewer than two goals in regulation until the Stanley Cup finals. That's great support for a goaltender, giving him a chance every game. Hasek is the best goaltender ever but Buffalo only needed a good performance from its goaltender to reach the finals in 1999, it wasn't the carry job that people often make it out to be based on Buffalo's roster.
Agreed. Lots of people on HFBoards think that Hasek singlehandedly carried the Sabres to the Stanley Cup finals in 1999, but that wasn't the case. I agree their roster, on paper, was weak, but you need to look at how the team performed in the playoffs. Heading into the Stanley Cup finals, the Sabres had scored 3.33 goals per game. Believe it or not, that was highest in the league (ahead of the Red Wings, Stars and Avalanche, who were all in the range of 2.95 - 3.10 goals per game). And defensively, the Sabres were allowing about 1.6 more shots per game than the average team (which isn't nothing, but it's not like Hasek was being constantly bombarded). Hasek, of course, was playing really well - but the Sabres were good enough that he didn't need to constantly steal games for them.
Giguere in 2003 is a different story. I think that's as close as I've ever seen to one player singlehandedly dragging his team to the Cup finals. After the conference finals, the Ducks had scored 2.36 goals per game (ranking them 7th out of the eight teams that made it past the first round). And the Ducks allowed nearly 36 shots per game (the worst out of any team that made it out of the first round). Giguere helped his team achieve a better record, with way less goal support, and while facing more shots against (nor did he miss two games like Hasek did).
Not that this is definitive, but another point to consider - the Sabres only played a single overtime game through three rounds (Buffalo beat Ottawa 3-2 in double OT, with Hasek stopping 15 shots in an extra 31 minutes of hockey). The Ducks played five OT games. If I've calculated this correctly, Giguere played about 161 minutes of OT, and stopped all 91 shots he faced. I'm not blaming Hasek for not playing more in OT (which is largely beyond his control), but it shows how much narrower Giguere's margin for error was.
We can also consider the "three stars" selections. Not that these are scientific, but just to capture how they were perceived at the time. In Anaheim's 14 games before the SCF, Giguere was named the first star in 9(!) games, and was one of the three stars in 11 of 14 games. In Buffalo's 15 games before the SCF, Hasek was named the first star in 3 games, and was one of the three stars in 6 of 13 games (he missed two games, so the team played 15 games in total). Like I said, I realize "three stars" selections aren't exactly scientific, and maybe there are different biases in different cities, but this all seems consistent with the team-level data presented above.
Also - it's easy to look at Giguere's 96.0% save percentage through three rounds and think it's similar to Hasek's 93.8%. It really isn't. Hasek's "goal allowance rate" (1 - save percentage) was almost 65% higher than Giguere's. Hasek, of course, was much stronger in the Stanley Cup finals, and I wouldn't object to someone ranking Hasek ahead looking at all four rounds. But there was a meaningful difference Hasek's 1999 run and Giguere's 2003 run, at least through three rounds, when looking both at their level of performance, and their importance to the team.