... 11-15 are substantially harder. The break really is the issue IMO. If you hit it too soft, you have a major cluster to deal with. Too hard and you have too many balls up table. ...
Maybe plan a rebreak either with a wasted shot or something like a 14.1 break shot?
Doing 15 more than half the time (now in 25 strokes) is supposed to be Efren/Gorst/Filler level of play.