Jeff Kaplan the secretly gay guy who recently left said they use Tracer as a base for character balancing. She's almost always "good" - like B - A tier in ANY meta no matter how balanced or unbalanced the other characters are. The fact this idiot doesn't even know about how the actual game plays or the meta around it goes to show how little this fucker knows about the game nor does he actually play.

Tracer is a pain in the ass to kill because she's quick, she hits hard, can teleport to confuse you, etc.