There is obviously some algorythm determing how seats are allocated in the DCS. On conventional DCSs, generally it starts at the front, allocates the window seats down both sides, then the aisles, then the middle seats. Groups/families are of course seated in the same row.
Don't forget that weight and balance constraints need to be taken into account too. Not an issue as long as a flight is fully booked, if it's half empty than allocating seats simply either by starting at the front or at the back might not be a good idea as it might cause W&B to go out of limits.
Somebody's most undesirable seat might also be somebody else's most desirable, there really is no way to know that.