This is pretty accurate with how the system works with one exception. In the last paragraph, the synergy works at a different level with the AI, so it is actually using both systems at the same time. Synergy helps to decide if a guy should drive, catch and shoot, pull up off of a drive, or finish at the rim.
As an example, if a player tends to pull up when challenged on a drive, if he's mid-drive and someone gets in his lane, synergy will influence him to 'shoot'. Real AI then acts at a lower level, looking to see where the defense is, what sequences a player has, and then pick the best one. It might select a cross-over -> step-back -> jumper, or spin move -> leaner, depending on the defense and what type of player it is.
These are recorded sequences played back on cpu players, so in that sense they are scripted. There are a number of aspects that make them organic in nature though. Firstly, they are playing back on a dynamic animation system. If a sequence has a spin, but you cut it off, the animation will not just plow through you. It also looks at where the defender currently is relative to the recorded sequence, and he's too far out of position, it can break out and choose a different sequence. In that sense it is just as dynamic as the underlying animation system, and with the two systems combined you get some really cool and varied behaviour.
We've never had something like this for performing moves - it has always been 'hard-coded' as to when to do a cross-over vs spin move, and it ends up looking very generic. In addition chaining moves into relevant combos was non-existent.
This isn't just signature stuff, this encompasses every move performed by the AI. More prominent players get their own specific sequences, but we also have sets for power post players for example, as well as even more generic "what to do when a user is trapping in the back court" type stuff. So far we have thousands of sequences, and at this point in the project, if we see a situation that needs a new one, we just record it and throw it into ANT.