The bad game design that means bosses will give chase to a single player or people who are close to death sprinting out the area just so they don't die. Three of us between lvl 15 - 31ish and a cp103 taking on Snapjaw and I admit, the fight was a drawn out affair. Just as the boss was around 1/4 health, the cp103 does a ruuner as they're obviously about to be picking up the daisies. Rather than just take it on the chin (no pun intended) like we all do from time to time, they run and we have to go through the entire thing again because the boss reset. They were about to do it again when one of the other people told the cp103 to just kite around the rock, but stay in the area even if it meant death.
If there's a group of players, the boss really should stick within it's spawn zone and no idea why they haven't added this mechanic into the game. Fair enough, If there's only a single player, then the boss should reset when that player leaves that particular spawn zone/cell.