One question, every second
A teamfight is chaos and positioning advice tends to be chaos too: stay back, stay with the team, kite, do not face check. The coach reduces it to one question, because that is what the footage supports:
If the answer to the second half is yes, you are about to be the target, regardless of how much damage you are dealing. A carry that dies in the first three seconds of a fight has dealt nothing.
What it looks like in your footage
The recording gives the coach every champion's position through the fight. Positioning in fight is tagged when the player's position, not the count and not a cooldown, is what made them the target.
- Closest ally to the enemy threat. At the moment the enemy assassin or diver commits, the player is the nearest ally they can reach. Not the tank; the carry.
- In front of the frontline. The player is level with or ahead of the allies whose job is to absorb the engage.
- No ally between the player and the threat. Measured as positions on screen: the line from the enemy diver to the player crosses nothing.
- Standing still while dealing damage. The player is stationary for several seconds, easy to reach because easy to predict.
Why the shape repeats
Range is a trap. A ranged carry's instinct is to stand where they can hit the enemy, and that spot is usually one where the enemy can hit them. The fix is not to stand further back in general, because then the damage never lands. It is to stand where the reach question has a good answer: behind an ally, at a range where the diver has to cross something to arrive.
There is also a fixation effect. A player dealing damage to a target watches the target. The diver coming from the side is not the target and is not watched.
The one change
This is a continuous adjustment, not a starting position. Fights move. The ally who was between you and the diver three seconds ago may have moved, and then so must you.
A drill for your next five games
In every fight, pick the single most dangerous enemy for you before it starts. Not the strongest; the one who can reach you. Then, through the fight, keep them on screen and keep an ally between. You will fire less in the first fights. You will also survive them, and a carry that survives the first ten seconds deals more than one that fires for three.
How the coach catches it
Leaguio Coach tags positioning in fight when the death frame shows the player as the nearest reachable ally to the killer, with the count even enough that position and not numbers decided it. The storyboard shows the frames through the fight so the moment the player became reachable is visible, and the readout names who was close on each one. Across games, the synthesis looks for the same shape with different killers, which is how "you are always the reachable target" becomes a named pattern with the champions listed.