The conquest catch-up system doesn't work on Mists of Pandaria.
Normaly if you don't play you gain a wider conquest cap depending on how many weeks you lost and depending on how much weeks the season is on right now.
The exact formula is :
(Week of the Season * 1000) - Total Conquest Points Earned in the Season = Bonus Cap
This bonus cap is added to your current cap.
For exemple, on my alt i have gain 5000 conquest points in total since s15 began.
It began around the first week of january = 17 weeks have passed.
So the formula does
( 17 * 1000 ) - 5000 = 12000
I should have 12k conquest added to my current cap as a bonus cap.
After caping the next week i will do
( 18 * 1000 ) - 17000 + ( my cap 2200 ) = 18000 - 19200 = -1200 so 0 bonus cap.
This is important because getting gear is becoming harder and harder as people gain rating and when you play an alt etc is it unfair for people at low rating to keep having to face "supposly" high rated people on their alts because they can't gain rating cause not enough gear.
Tip : This bonus cap is added to the arena cap.
Tip#2 : This feature doesn't destroy how people are going to get gear. New characters aren't supposed to be affected by this system until the level 90 because the cap and rating is supposed to reset when you gain levels.
They will get a good cap to catch up on fully geared people when they hit the level 90 for exemple.
Tip#3 : People with alts will be able to gear them quite easily without spending 3 month for it but i doesn't say that they don't have to play the game to get gear. They still have to play and it this feature can bring a good balance to the PvP Arena since alt of Gladiators etc High rated players will get rating fast since they will get gear and not bother low geared people or Low rated people.
Messageby Blizzard :
"Mid-season catch-up for Conquest Points has been added. Players will now see their cap on Conquest Points increased by 1000 per week since the start of Season 13 minus the amount of Conquest Points earned so far in this season"
A few post about conquest catch-up :
http://us.battle.net/wow/en/forum/topic/9164976601
http://us.battle.net/wow/en/forum/topic/8796272076
The Original topic http://us.battle.net/wow/en/blog/8397168/PvP_Gear_in_52_and_Beyond-1_17_2013
