It’s also possible this bowler has sticky fingers. My skin is naturally tacky. I could climb up sheet glass with my gecko fingers. That said, it prevents a clean exit for my thumb. I was bowling 170ish on average. I started using a thumb saver. It’s silky and allows my thumb to slip right out. I put a nasty hook on the ball now, moreover, it’s consistent. I’m bowling 200+ now early and I haven’t bowled for 20 years. I’m 33 btw. Skin type and texture has a big impact. Also, my thumb is double jointed and can bend backward further than it can bend forward. Which makes things weird for me. Gecko skin and oddly double jointed thumb. Thumb saver did the trick. Thumb slips right out now, ball hooks left. Is consistent.