Cbops is an interesting metonymy. It means the mouth and jaws, in slang, and thus the brass player's (or sax's) embouchure. (Even singers talk of embouchure.) "the way in which a player applies the mouth to the mouthpiece of a brass or wind instrument."
Since the embouchure is vital to technical proficiency, chops becomes the favored metonymy for technical proficiency on a wind instrument. The next stage in the use of the word is that players of other instruments begin to use the word for technical proficiency. A piano player or drummer. I can honestly say I have very minimal chops on the keyboard. The word spreads from jazz to other styles of music, and from wind instruments to other instruments. My dictionary derives chops from chap, but I always thought it derived from choppers, slang for teeth.
Now we can extend the meaning to non-musical endeavors. We can have chops taking photos or writing scholarly prose. It all comes from the mouth, or embouchure, the point at which the human voice emerges from the body.