I recently ran into two dps that did that. Mind you it is, perhaps, one of a handful times for me since the start of ARR. Annoying non the less, even though they are rare.
First: I always pull big, I always pull the boss as soon as all are close enough, no countdown, no standing still. I had the healer on voip so no problems there.

The first stupid thing was one dps pulling the first pack, but I picket them up and sprinted further, gathering all them mobs up nice for some aoe, they did aoe but not the fastest I have seen so to say.
Then that same dps ran in an pulled the first boss, I let the dps be hit a few times before I picked it up. They want to pull then they clearly want to tank, so I gave them a taste. Again, the time to kill on the boss was not the fastest.
After that the second dps, a range, pulled the first group of mobs after the boss, I told the healer I would ignore them and continue, the dps now made the right decision and came running with the mobs after having been hit by them more then they clearly thought they would, they also did not get any heals until they had the mobs where I wanted them, of course I took the mobs from them at this point.

The result: The dps did not repeat their mistakes, they did not say anything about it either, I got to do the pulls smoothly without further annoyance. A happy ending.