Characters below level 50 can no longer queue for the Mists of Pandaria scenarios. Before the pre-patch, if you locked your level to 90 you could queue with other level 90 characters to get a Greater Cache of Treasures. Now, if you are level 35, the level cap for Mists of Pandaria, you cannot do this anymore.
These caches contain two unique transmog sets that only drop from them: Azure Serpent Set (Recolor) and Firewool Regalia. Apart from being rewarded from queueing for MoP scenarios at the appropriate level, the caches are a reward for three quests: Heroic Deeds, The King and the Council and The Warchief and the Darkness.
Before the patch, you could make a trial character to pick up these quests, run the scenarios and have a chance at the unique transmog set, generally a lot faster than queueing on a level-locked character. After the patch, trial characters are level 48 and cannot queue for Mists of Pandaria scenarios.
After the patch, all you can do is those 3 quests on a level 50 character and that's it. If you want another small chance at the unique looking items you have to level another character to level 50 and do the three quests, meaning these two sets have become practically unobtainable.