Tampa and Boston both have veteran teams that know how to win and are used to it.
But both also have aging teams, and have been hemorrhaging draft picks since forever, to the point where their prospect pipeline aren't that great.
There's this thing about the King(s) on the hill, people get used to them and assume they'll be there forever. But their reputation always end up living longer than their true prowess. Older players aren't hungry like they used too, they won before and they don't necessarily have the same fire in them. They change, they have families now, they get complacent. And suddenly here's a younger team, one more than ready to steal the crown, more hungry, more desperate, more resolute.
You don't kill the King by staying home and waiting he dies of old age. If you want to become King, you need to take action, you need to assert yourself.
It could only take a bad season, a few bad injuries to key players, and both Boston and Tampa could see their window close and their team crumble. They'll hang up as much as they can, but this is a cyclical league, and they are on the wrong side of that cycle. And all it takes if for some younger team to plant the seed of doubt... It won't be easy, but it's not supposed to.