They definitely want Brady to stay fresh and be prepared to come back and shred the NFL. Fortunately for New England, he's staying warm by chucking the ball around at home.
I mean, what are you gonna do? Brady's teammates are all hanging out in Arizona (well, except for Rob Gronkowski, but he's not running routes with his busted hamstring) and he's got no one to throw with.
He's probably hankering to toss the pigskin around, and there's no one he can throw with. So he and Gisele went out in their football field-sized backyard and winged it around a little bit.