As much as it pains objective analysts to acknowledge, building a championship-caliber NBA team is as much a matter of chemistry as it is arithmetic. Things are never as simple as they seem on the surface. That probably will be the case regarding the Mavericks' acquisition of Rajon Rondo.
The Mavericks are in between the extremes of lottery and elite, and that's probably why one of the league's boldest franchises was willing to stir up the mix of a team that was historically good on offense but well below title-worthiness on defense. NBA teams often operate as if they're under some sort of Hippocratic oath: If something is working well, do no harm, even if your ceiling is below a championship.
Under Mark Cuban, the Mavericks have never operated this way, so this latest stroke of boldness is no surprise. But understand: Any move Dallas could make would be a threat to its top-ranked offense. No other offensive group has ever been this efficient; if you alter it, you're going to become less than that. So by bringing in a player as prominent as Rondo, Dallas is banking on improving its defense to a degree greater than the harm that is sure to befall its offense.