Rotations done correctly put officials in the best position to see plays, when a rotation is missed, officials can be caught off guard.
Rule 4-7-1 – Blocking is illegal personal contact which impedes the progress of an opponent with or without the ball.
In the following play, the offensive player makes a move to the basket. A secondary defender comes up to attack the drive and commits a foul on the dribbler. This is not an uncommon play, it happens in every game. When the official is in a position to pick up this secondary defender, it is an easy call.
However, in this particular play, the lead rotates over to the near side. The old center position is in a good position to referee his play, so he delays his rotation just a moment to finish refereeing his primary matchup. Once the play clears, he begins to rotate up, but it is too late. The contact has already happened and it has moved out of his primary coverage area. Who should have this play?
The trail official gets caught out of position, just for a moment, and it cost the crew this call. It is ok for a center official to delay completing a rotation in the name of maintaining a good position to referee the play. However, there isn’t really ever a time when it is ok for the trail official to delay a rotation. It is far better to have 2 center officials for a moment than to be caught out of position on this play. If the old trail, new center (on the far side) had rotated, this play would have been in his lap.