I really don"t remember what I said back then. However, as I look at the situation today I can elaborate on not only the shot Frost chose, but some other options as well. After looking at the results of the shot Frost chose and understanding that he needed to hit deeply under the lead ball with the combination.... in order to pocket it... leads me to believe that he should have drawn the ball with speed. Shooting the shot in this fashion would have guaranteed a better direction with the cue ball and a higher percentage of ending up with a shot on either the 2-3- or 15 balls.
If playing the cue ball to the upper left corner as an option for a conservative move was your choice, then you must be concerned with leaving your opponent an easy side rail kick to the opposite side of the balls that formed the combination you just passed. For this reason is why I liked banking the 12ball to the pocket and leaving the cue ball at the upper left end of the table. I would have then favored leaving the cue ball where I wouldn't leave the kick and at the same time trying to position the 12ball as a problematic ball for your opponent.
Dr. Bill