The biggest problem is more mandatory stall calls have made refs ignore non-mandatory ones. 5 seconds on the legs is stalling, but 4.5 seconds 5 different times is 22.5 seconds of legal riding time. If a guy continuously drops for 4 seconds, call stalling. Not attempting a mat return is a stall, but letting him stand for 4 seconds and then pushing him out of bounds isn't stalling on top. The problem isn't the rules, the problem is refs refusing to call obvious stalling.