I wouldn't call that a good game. At least not by his standards.
Well, first off, that says that his standards are off the charts great. It's like saying, wow, Michael Jordan only scored 28. He sucks.
But second, he really did play well. He made one major mistake, and even that was defensible. Let's take an objective look at his game.
(1) The safety. He had to get rid of the ball. Why would he throw it where he did? Because, as Steve Young pointed out at halftime, that is NEVER called intentional grounding. As in, ever. I'm sure Brady threw it to a spot where he knew nobody could get to it, and where it's never called a penalty. I'm sure he felt very safe putting it there. He probably was as shocked as anyone that a flag was thrown there. So I guess that was a mistake, but the kind of mistake that is totally understandable.
(2) He ended up, at one point, being 20-23, with the three incompletions being two JPP tipped passes and the grounding (which, even if it wasn't grounding, was a ball he had to throw away due to the pressure...can't fault him for the INC). So he was right on the button through 23 passes.
(3) Then he got sacked by Tuck, which obviously hurt his already injured left shoulder. From there you could see that his accuracy was off. And he finished 7-18 from that point on, which sounds horrible until you realize that (a) he was due to cool off, and (b) you take into account his injury.
(4) The INT. This was his mistake, and he'll kick himself when he sees the film and notices Hernandez wide open on the right for about 15 yards. But here's why it was defensible. You have Gronk deep, and he beat his man by about 3 yards. You have what amounts to a backup linebacker on him. You could throw that ball up there a hundred times and probably only on one of those occasions does it end up as an interception. Well, guess what, that was the one time. So it was the wrong play...the big mistake. But even that mistake was a defensible one.
(5) The drops. Pats players had, I believe, 4 drops on the day. One was a tough catch (Welker), but by everyone's admission, that's a play he makes far more than he doesn't. It wasn't a perfect throw, but Eli had some non-perfect throws too that got caught.
In the end, if you take away the spike and the hail mary, Brady finished with a 69% completion rate, which, as it turns out, is essentially the same as Eli's. And take away the batted balls and the "have to throw it away safety", and the drops and Brady ends up completing 27-34, which is a 79.4% completion rate.
Now, one may say, but you can't take them away. And of course you can't. But if you're assessing how Tom Brady did throwing the football, an objective analysis takes these things into account. The Giants didn't drop a single pass, and they made several outstanding catches to help their QB. The Pats dropped 3-4 balls, and nobody made even one outstanding catch to help Brady. Plus, Brady had the hail mary and the spike and the "must throw it away" play where he wasn't trying to complete it. So on passes that Brady was actually trying to complete (that had an actual chance to be completed), he was tremendous.
He wasn't perfect. But you know what? Neither was Eli. He bounced a bunch of balls into the dirt. He threw really high on a ball that Nicks made a crazy good catch on. He was really good, but not perfect. Same with Brady, who got no help from his receivers at all on Sunday.