Eli made critical throws in both games. So, yes, he did win it.
Furthermore, are you saying that the Giants offense in either of those Super Bowls was better than the Cowboys offense of today?
Look, the stronger unit usually is going to win the Super Bowl for a team - or get them there. But it's not an absolute certainty that if your defense is better than your offense, you're going to win the Super Bowl.
In fact, since 1993, 12 of the 25 Super Bowl winners had better offenses than defenses (
https://www.reddit.com/r/nfl/comments/9r7q6x/the_last_25_super_bowl_champions_and_their/). Two of the 25 winners were equally balanced offensively and defensively. That mean the Super Bowl winners over the past 25 years had better offenses than defenses.
In the case of both Giants Super Bowl winners, the offenses were ranked
HIGHER than their defensive units. In 2011, when the Giants won, there offense was ranked 9th and their defense was ranked 24th.
My conclusion: We have the ability on offense to get to the Super Bowl, theoretically speaking. And our offense is better than our defense. So this doesn't provide an excuse for Dak. In both of Eli's wins, his offense (and he was the focal point of their offense) was better than his defense.
Eli may have gone out on a whimper, but he was not merely a bus driver for his Super Bowl teams. Statistics prove otherwise. He stepped up when it counted. And if the name of the game is winning Super Bowls, who cares if he was pedestrian in the regular season. I don't care if you can swim when I'm in shallow water. I need to know if you can rescue me when I'm drowning. That's when I care if you can swim.
More to the point, I don't care if Dak is great in the regular season, just like Giants fans didn't care if Eli wasn't John Elway. When he got to the post-season, he turned into John Elway even as the defense stepped up its game.
We need Dak to do the same thing, especially since he has the talent on offense. That's the standard we have as Cowboys fans. Unfair? Maybe. But he can always go somewhere else if he doesn't like the standard.