Doing some reading, it appears none of the scouts like him because of his delivery. Yet, he's been an excellent reliever at all levels thus far. The Cardinals haven't messed with his unorthodox delivery because it puts very little strain on his arm. Then the results have been excellent. Link
to his career stats. One strikeout per inning guy every where except 2007 winter ball (only 5 games though).
Just do a Google Search on Mark Worrell and read the first few articles.