SM2K, when Venus is making very few unforced errors, she is usually controlling her power very well, keeping the ball in play, and moving her opponent around. Venus with 15 or less unforced errors = Venus on top of her game. This also includes serving extremely well (power + placement), forcing her opponents into long tiring rallies, coming in to the net on short balls (forced by her powerful and accurate groundstrokes), and most importantly, stealing her opponents confidence.
In other words, it is nearly impossible because 15 or less unforced errors from Vee, probably means a flawless game from Vee.