Here's some food for thought. At the PBR Finals, I divided the bulls up into 2 groups using the average power rating (which is a way to measure difficulty) for UTB events (around 73)

The "above average" group

Power rating 73 & up

227 outs

30 qualified rides - 13.2%

Avg. mark: 21.77

The "below average" group

Power rating under 73

58 outs

23 qualified rides - 39.7%

Avg. Mark: 21.51

If you are a bull rider, which group do you want to draw into?