But I am not sure if a good deal of his bad luck is not due to the merciless way in which he was laughed at, and called "duffer," and taught to believe that he could no more do a thing right than a bull could walk through a china-shop without making a smash.

He got it into his head he was a duffer, and therefore did not take the pains he might have done.
"What's the use of my bothering?
I'm sure to make a mess of it!" Fancy a boy saying this to himself at cricket, while a ball is flying beautifully towards him, an easy catch, even for a duffer.

Do you suppose he will catch it?
Not he.

He will stand where he is, and put up his hands, and look another way.

In fact, he won't do his best.