A Fighter by his Trade

I am recalling the opinion I gave on Fib's site about the S&G lyrics to "The Boxer." After reading through the entire song, the meaning has become quite apparent, indeed. Meh, it's SO freakishly clear, I don't know how I missed it. But to explain it coherantly...*laughs grimly*: The boxer is a semblance of who the singer was--a fighter. As a boy, he resisted ridicule (for being poor, maybe, or whatever), possibly verbally, possibly physically, what have you, until he "squandered his resistance for a pocketful of mumbles." Instead of continuing to resist the ridicule, he just mumbled a response and stopped fighting; he accepted the opinion of the unnamed antagonists. He walked away. The singer is lamenting for the fighter he knows he still is, somewhere deep inside (I am leaving, I am leaving, but the fighter still remains/ Yes, he still remains). It's a brilliantly coined line, really.
How did I miss that?

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peccadillo (n. A slight offense; a petty fault)