#1 - March 13, 2013, 4:34 p.m.
Blizzard Post
Longer explanation:
Traditionally, trinkets and similar proc effects in the game had high proc chances with an internal cooldown (ICD). This made the procs random in theory, but really pretty predictable. You would know that a trinket would proc on the pull and then reliably every 45 sec (or whatever the ICD was).

For 5.2, we made a change to trinkets to make them less predictable and less boring with the RPPM system. Sometimes you can get lucky and get several back to back procs. This feels cool. Sometimes you can also be unlucky, and get long streaks when the trinket just refuses to proc. A trinket that is intended to proc every 1 minute could in theory go 8 minutes or more without activating.

Last night we hotfixed in a change for trinkets that use the RPPM system. Every time your trinket fails to proc, it increases the chance it will proc. Unlucky streaks will be more rare and extremely unlucky streaks should never happen. In addition, we increased the chance for these trinkets to proc on the pull. To top it off, we increased the proc rates of the Agility and Strength trinkets in Throne of Thunder by 10% and the Intellect and Spirit trinkets by 5%.

Painfully detailed explanation for theorycrafting:
As usual, you absolutely do not need to know or understand the following in order to use or best take advantage of these procs. This info is just for theorycrafters who want to understand the exact details of the system, so that they can model and simulate it better.

Calculate the proc frequency as normal. Based on that, you can figure out the expected average proc interval. We also now keep track of time since the last successful proc (this is different from the time since last chance to proc), capped at 1000 sec. Multiply the proc chance by MAX(1, 1+((TimeSinceLastSuccessfulProc/AverageProcInterval)-1.5)*3). For example, if a proc has an average proc interval of 45 sec, and it’s been 72 sec since your last successful proc, you’ll get a 1.3x multiplier to your proc chance. If you’ve been out of combat for a few min, and it’s been 5 min since your last successful proc, you’ll get a whopping 16.5x multiplier to your proc chance.

We increased the proc rate of the following trinkets by 10%:
  • Renataki’s Soul Charm
  • Talisman of Bloodlust
  • Bad Juju
  • Rune of Re-Origination
  • Fabled Feather of Ji-Kun
  • Primordius’ Talisman of Rage
  • Spark of Zandalar
  • Gaze of the Twins

We increased the proc rate of the following trinkets by 5%:
  • Wushoolay’s Final Choice
  • Breath of the Hydra
  • Unerring Vision of Lei-Shen
  • Cha-Ye's Essence of Brilliance
  • Horridon's Last Gasp
  • Inscribed Bag of Hydra-Spawn
  • Stolen Relic of Zuldazar
  • Lightning-Imbued Chalice

Unerring Vision of Lei-Shen now has 65% of the normal proc rate for Balance Druids, up from 50%.