Against enemy heroes. Like, let's take Genji for instance. There are lot of Genjis that can hit M2 and murder you pretty consistently. They can hit E with decent timing and know all their stuff. But when they run into specific heroes how many actually put thought into their jump patterns and spacing? Or hold E > shift to deal with a specific CD? Or use shift to go through certain CDs (yeah you can do this vs flashbang) while holding onto E?
Another example is just knowing the MU. Like McCree flashbang doesn't stun if it hits behind an opponent; they have to be facing it(well, kinda, the hitbox just doesn't really go behind where the flash ends up to get this effect. Easy to visualize this way). So vs Tracer how many McCrees will walk forward, knowing Tracer blinks into him to beat flash, then does 180 into flash because he has the spacing and she can't react in time after she adjusts?
It all adds up.
It's mostly knowing where on a map they have advantage and when they should just move because they lost advantage. A lot of people just sit on high ground and refuse to drop or move backwards until they get jumped. When I see a player start to move backwards the deeper I try to move in on them, the more scared of them I am.
On the flipside, the normal problem of not being willing to move in and shoot is still an issue
you gotta be able to move while speedboosted and hit shots and know when to make the call on when to do it. That's kinda counter intuitive to most FPS to run at people with a hitscan hero for instance, but it's really good.
This is the core of why most diamond players are diamonds. Yay, you hit sleep dart on Soldier and he died. Huzzah, you are awesome. Then McCree ults and your entire team wipes. If an ult like that is charged, sleep dart as a confirmed kill is a lot less valuable unless you have good positioning + Rein shield.
Also a lot of Anas will take 50~ or so damage and then nade themselves, Then when their tank gets dove they have no nade to heal him, or when a nade can literally wipe an entire enemy team they don't have it. Lucio will blow E (the single best CD in the entire game) for mundane reasons before a fight is fully engaged, then the enemy team dumps all their damage CDs. Lucio is then confused how his team died when that one E he did made it so the team had no counterplan for damage coming in.
Basically every hero in the game is anywhere from half as strong to near useless without a CD being up. Again, it's MOBA 101 but people miss that in an FPS game. Lucio is basically useless without E. McCree without flash is the most free dive out of all the DPS.
You mash all that shit together and the end result is that if somebody stays out of position for one second they get punished and might not know why. Somebody might get reward of a CD and then have their entire team wipe because that CD was down, and then they are confused. Meanwhile at higher elo if I whiff Helix and am not firmly in my tanks ass cheeks I might as well have held up a "kill me now" sign.