Say you do ICC25 HC every week. Festergut is on "farm" status and every DPS tries to max their DPS out for fun.
You start out with x DPS and then get an upgrade. So your overall damage will increase and your DPS will go up as expected. But since you do more damage the fight shortens causing you to be under the effect of cooldowns for longer - so DPS rises from that too. Is that right?