India, Nov. 1 -- New Delhi At this edition of the Indian Premier League (IPL), two classic, highly coveted bowling skills have ruled the season: the yorker and the googly. With IPL13 being played at only three venues bowlers have had to be more imaginative. Be it the slower bouncer and low full toss for fast bowlers or the flippers and quicker deliveries for spinners. But if the main purpose of bowlers is to be economical then CricViz's ball tracking data suggests that yorkers have been the most effective variation this time....