The Bucs have retained their top FAs. Godwin, Shaq and David were rated at #1 in their positions going into FA.
The Bucs just won after dominating in the playoffs. The team clicked at the end of the season.
You do make a good point, the team could come down to earth and be soft after winning. But that's where Brady's leadership takes over.
Brady knows how to stay hungry after success and that can help his teammates stay focused.
But I agree you can't just pen the Bucs into the Superbowl. The NFC is still a strong conference