It's not new. Killing your opponent essentially is getting your opponent below 50% Health. This is very nice if you can plan around it, which can be difficult in PvP.
For example against Darkmoon Faire trainer I use a Infinite Whelpling against the Eye.
1. Tail Sweep.
2. Tail Sweep. Eye will now be below 50% so dragonkin racial kicks in. This will be overkill so in turn I won't attack.
4. Tail Sweep. Kill the Eye and dragonkin racial kicks in again.
5. Early Advantage with Dragonkin Racial will pretty much kill off the Darkmoon Tonk.
This is just an example. But if you can plan around it you will really improve your damage output.