Well, the gear gap is becoming less of an issue now that you can get Centurion about 5x faster than before. New 50's don't have to be fodder for quite as long.
But it's true, if you bracket it based on expertise alone, new 50's would be thrown in with people with PVE gear. It would be better to bracket it by the sum of the item levels, or some such.
The easiest for them to code would be Valor Rank, but that doesn't necessarily equate to actual gear, or skill for that matter.