I can't think of a way to really analyze it statistically, but it certainly seems like we have seen an awful lot of great sports performances by athletes who were suffering from the flu at the time. The classic example is MJ against the Jazz back in the 1998 finals, but it seems to happen really often.
I always wondered how that was possible, but Teixeira has an explanation:
When you [play with the flu], for some reason you get more focused, because you know you can't do everything you're used to doing. You're slower and your body hurts a little bit. So you focus and you're going to have nights like this.
That makes sense to me. It also reminds us that, despite the monster athleticism of anyone good enough to make the majors or the NBA, focus and mental discipline is what separates those who are simply gifted with athletic prowess from those who are truly elite.
Speaking of Teixeira, his line since being acquired by the Braves is .294/.388/.745, with 9 home runs and 25 RBIs in 18 games. The Braves haven't been setting the world on fire since they acquired him and haven't made up any real ground on the Mets, but that's certainly through no fault of his own.
Even with their middling play, however, they now stand only a game back in the wild card standings. With two strong starters, a lot of bats, and Teixeira in tow, the Braves may have a better chance of making more noise in the playoffs this year by squeaking in than they did in most of the years in which they coasted in.