Counter Swap
Switching heroes to directly counter an enemy pick and nullify their advantage.
With 5v5 cutting tanks down to one, the impact of a single counter is doubled, so when and who swaps (tank first or DPS first) dictates the tempo of the match. A swap is double-edged in that it also hands information to the enemy, and since every fight becomes a read, holding and not swapping is itself part of the tactics. There is an argument that over-swapping backfires in ladder, but top pros treat responding to an enemy pick change within two fights as the baseline.
When the enemy swaps to a hero that exploits your comp's weakness. On the reset after a fight where the matchups were clearly losing.
Being unfamiliar with the hero you swap to, making the matchup worse instead. The enemy holding a further counter, turning it into an endless swap war. Swapping mid-fight and collapsing the formation.
Resource Trade
Spending a minor cooldown to force a major defensive one, netting an advantage for the real fight.
Tempo
The initiative — who gets to choose when and on whose terms the next fight starts.
Fight Reset
Choosing to disengage from a stalled or losing fight in order to rebuild formation, cooldowns, and HP.
Comp RPS
The rock-paper-scissors relationship between Dive, Poke, and Brawl that shapes drafting decisions.