Ehhh.. I'm taking that with a grain of salt. It's too early to tell. If CMB does actually keep up the momentum it's probably not even going to be peaked by then. 
But the Grammy's would be the perfect spot to perform a new song. 
Think of the sales 
But if CMB is just nearing it's radio peak.. I'll need her to perform that so it achieves the maximum peak position. It would probably definitely be a Top 10 on the Hot100 after that.
PLU has a chance to make it without the Grammy's if she gets some Idol promo or something.. it's a more obvious smash than CMB, so.... 
It's actually a really difficult decision.
PLU might sell the album more than CMB so maybe it is actually smarter to focus on album sales than single sales/success for CMB. 
