if Dallas got worse, it follows that we got better.
Silver linings.
I don't think that's necessarily true.
You're right that it's not necessarily true, but in this case it actually is.
It's all dependent on positions and system. Jeff Green was clearly a better player than Perk, but when Boston traded it's starting center for a backup SF, it didn't necessarily improve them.
Boston could afford to lose ROndo, because he didn't fit the system and what he brings to the table is overblown. Guys can step in, the offense can adjust and we'll be better off.
Dallas had a system built around spacing and ball movement... they already have one ball-dominating PG. Adding Rondo has the potential to hurt them.
At the end of the day, Boston will still be a bad team and Dallas will still be a good team. But I don't see this trade making a significant difference for the Mavs title push. They could miss the playoffs if they struggle like it appears they should on paper.