Based on David O'Sulovan's video on Facebook, urethane balls often create carrydown from a lack of flaring. Asym cores on urethane might be the way to go.
Also can't believe there are people saying urethane should be banned.
I guess when I bowled a tournament this weekend I ruined the shot with my Purple Pearl Urethane and its carrydown. Funny thing is, a guy that followed my pair beat me for the 8th games by 13. I guess I should "learn" how to take hand out with reactive even though the shape that this ball provides gave me the best opportunity to score.