Pantheon's high winrate is the result of games being decided way too early.

He's a champion with obvious weakness in teamfighting. Fighting other fighters straight up before he is able to poke them down. Late game isn't so great for him.

It's either early game should not dictate the outcome of the game so heavily, leave Pantheon be in this case. Or keep the game so the enemy jungler gets two kills and it's GG and nerf Pantheon. Latter option is pretty much only if people see Pantheon as annoying or an issue. I rarely play against Pantheons so...

Whole post is making the assumption that Pantheon is annoying(maybe)/unhealthy(maybe)/OP(maybe) so...