I think their percentage has little to do with anything if they are paid cappers ... They are professional because they get others to pay them for their plays. Their plays are often pathetic, but that's not the point.
Most are crooks who really enjoy tricking people into paying for BS. They would derive no pleasure by selling a solid product for a fair price.
That's not their style.
Apparently if people capping for themselves can make 55 percent they've done pretty well. At -110 lines you're winning by 53 percent, and killing it at 55 percent. So if you're at 57 percent, very very good for you!!!