Lakers defensive system shares the same fundamentals of Celtics' system, for example. It's a quasi-zone, stressing over-help, with the goal of crowding the strongside and stop dribble penetrations. The C's put more emphasis in protecting the paint while the Lakers are more focused on attacking the ball and the passing lanes, fronting the post, creating havoc, trapping the ball handler and causing turnovers. The most similar system is probably the one that George Karl uses in Denver, he learned it from Coach Kloppenburg during his tenure in Seattle, I think.
This kind of defensive systems are generally vulnerable to crisp and quick ball movement, skip passes, good outside shooting from the weakside, bigs who can play in and out and are quick moving to the empty spaces, and balanced offensive weapons - it makes life more difficult for teams that rely on their stars to carry the scoring load (like most NBA teams). It's the kind of defense European teams play and the better way of beating it is by playing the kind of offense European teams use.
Anyway, defensive schemes don't matter that much. Verbal communication and good individual defenders are the foundations of good defense, not x's and o's. They added a strong defensive presence in Bynum, a healthy Ariza, who is a great player to have in this kind of system because his combination of length and quickness allows him to be a disruptive presence and Kobe, who is an excellent commander-in-chief and keeps everybody talking and accountable. More than the new schemes, those are factors that are making their defense so good. But when it's all said and done, it's going to be about execution. If their perimeter defenders can't force the opponent wings to the baseline or wherever they have the help, the system will eventually fall apart: over-help systems are great but, at some point, the help chain collapses.
