Knebel has got to find a way to limit the long ball. He's given up 6 HR this year, more than Hader, Jeffress, Soria, Williams, Barnes, and Jennings, all who have thrown considerably more innings. Hitters seem to be picking up when Knebel is going to stay with the fastball and are just crushing it. A tendency to give up walks plus a tendency to give up HR is a really bad combination, especially for a closer.