Cassidy should be called Banger, because he bangs. This should be his hero name, literally. Banger.
Think about it; He bangs the baddies in many ways, like throwing his flash bang. Or with his gun, for example. One of his sprays has the word “bang”, and he sometimes says it after an elimination, so were halfway through with this rebranding already.
His catchphrase should be “Bang”, and he would use it as an interjection in everyday speech, always trying to slip it into any exchange, no matter the situation.
I got some voice lines ready too:
“That there was a bang-up job”
“I have a Big Bang Theory of my own… wanna hear it?”
“You were hankering for a bange- heh 'scuse me!”
Well, her name is not because she traces but rather because her blinks reflect the tracer of a tracer bullet, which is a visible stream left in the bullet’s wake.
However I support your plans for McCree and his banging.
Isn’t Tracer’s name technically “T-Racer” (that’s how she pronounces it in her voice lines) which I assume is “Time Racer”. She races through time blah blah blah.