Just that you basically have to have somebody dedicated to playing a DPS character that has ranged hitscan on the team. Not projectiles, just somebody who can shoot at range and register hits instantly. Certain characters, like Pharah and Mercy, exist where you just have to have a solution on hand to deal with.
First ver this was Widowmaker, last patch it was Soldier, this patch it's McCree. Just whoever has the best ranged hitscan DPS will be almost autopick on any team. You only wouldn't see this when teams had more specific comps going or there was some map condition driving them into something else.
Like, McCree vs Soldier will be I guess an interesting choice to make this patch, but McCree is a bit overtuned and the raw damage is just valued more over Soldier's utility in most common situations :T