If you're waiting for a 77% chance to steal home, you'll never steal home in your life. It's a straight -9 off the second number (pitcher's hold and catcher's arm don't enter into it), and you rarely see a second number higher than 15, so you'll hardly ever see a chance better than 30%.
46.2% on steals of home is honestly rather astonishing, and I bet represents a lot of lucky rolls
I'd sure as hell take that success rate, at least if the attempts were with two outs, or maybe one out and the #8 hitter up in a non-DH.