@xo74e2o828e2 chances are in buckets of 10 - the average player will take around 15 chances in a match and score between 10 and 13.
As you have only taken 11 or 12 chances, you have only dipped into one or two chances from your second bucket whereas your opponent who has played their chances quicker has had 15 chances, so five picks from that second bucket.
VSA is all about getting through your chances as quickly as possible - it is no point taking ages to try and score a basic chance by passing the ball around when you could try a quick shot and then move onto the next chance which will likely be good or great.