You're going to lose 80% of the time. Most people build their whole identity inside the other 20%.
It's your ego that thinks you're supposed to win. Three ways to shift to mastery:
Move the mirror off the scoreboard. Track hands ready, butt down, talking on defense, reps after you wanted to quit. Something you can go 3-for-3 on in a bad week.
Protect the unglamorous hours. The Thursday in February when nobody's watching. Nobody claps for those reps. That's why they count.
Refuse the label. A win is a data point, not a verdict. If mastery is the point, the championship is just one particularly good Tuesday.