I won’t pretend to explain a defensive game plan because not having enough information about it, but I can show you some details of CSKA’s defense during the third play off game against Red Star. If you want to get a deeper understanding, my advice is to analyze those three games to find out how it works.
There’s an old saying in basketball “the best man to man defense looks like a zone and the best zone defense looks like a man to man”. That could be the idea behind the defense we saw in the mentioned game. We can argue about the way we call it (switching man to man, flexible zone, mutant defense) but there’s no need to go crazy about it.
In my opinion, CSKA has the personnel to try this kind of switching defense. Their physicality and size allow them to go for it not giving up a lot of advantages to their rivals. But there’s another idea we should keep in mind. The defense’s “first stone” is not the switching, but the 1 on 1 and team communication. Bigs need to make efforts to guard smalls and smalls need to be really aggressive, as they will find themselves in a quick mismatch situation quite often. Then, the focus to switch or rotate when needed is also a must.
Also, the scouting work matters, Red Star use very often “horns” situations, as well as quick side screens. This switching defense may create problems and definitely slow down the rhythm of the offense.
Some of the rules they appear to be following:
They place a “big” on top of their defense (Kurbanov, Nichols)
They switch high ball screens avoiding an advantage for the “roll man”, and try to keep a small guarding the ball after the first switch.
Continuous attention to the ball’s position and players’ movements
Be aware of cuts, to follow and/or rotate, trying to stay in the same lines. "Smalls" defending outside spaces, "bigs" close to the basket.
Sag off from your man when the ball goes inside
If the mismatch finally happens: FIGHT IT. No easy penetration, no uncontested shots, no easy passes inside (defender in front) Off ball activity.
Let’s take a look: