You are the top player of your football league. Your dribbling is so good, that you can practically dance around defenders and score individual goals. Nobody can stop you. So you move to the next league.
The defenders are now tougher, and you cannot get past them easily. When you try your usual tricks, they fail. So you need to unlearn them, learn how to pass and involve your teammates more. At some point, you get so good at this that you can score whenever you want to. That is when you move to the next level.
At this advanced level, defenders are keen at anticipating your passes, and they shut down your team’s play. You need to unlearn again, and learn something new – to combine dribbling, passing and clever movement across the field.
And then, you need to factor for injuries. At some point, you inevitably get injured. As you recover, your game needs to change to prevent such an injury and still sustain your level. Once again, a whole bunch of unlearning and learning.
The path to mastery isn’t a straight line from beginning to end. Instead, it is made of several circular loops of learning, unlearning and learning again.