A few things in life that you cannot dispute: Water is wet, the sun rises in the east, and Trannies LOVE Lady GaGa. Trying to get MCR to admit that Christina has a better voice is a fruitless endeavor.
With that being said, Christina was awful yesterday and as KEK has already pointed out, there should be no excuses for her. The girl from Glee came on right before her and did just fine. I also doubt that she has performed for anywhere close to the amount of live audiences that Christina has.
As far as the Halftime show, would it be such a sin to bring somebody in who can actually rock the house? I'm not talking about old rockers either. Football is a violent sport and deserves some high-octane, in your face-type of rock music that's a little more contemporary than Mcartney, The Who and Tom Petty.