For those that aren't familiar with Death Knight mechanics, the Runic Corruption talent differs from both Blood Tap and Runic Empowerment in that it speeds up Rune Regen greatly when it procs, rather than fully activating a depleted rune.
This find however, seemed to imply that a bug was also causing Runic Corruption to affect RPPM rates: Trinkets such as Feather and Rage, the Capacitative Meta and even our Tier 15 2P.
We discussed this in #Acherus and were unsure if this was a bug solely restricted to the PTR or one that had been present since 5.2 (anecdotal evidence suggested it had, but we wanted more proof).
It also stands to reason that if Runic Corruption is behaving in this way, then Improved Blood Presence and Unholy Presence are likely doing so as well.
Mione (Mioneechan on Kazzak-EU) was kind enough to assemble some parses for us, so full credit to her:
The following are roughly 30 minutes logs of pure autoattacking on training dummies, as Blood spec, one of them being done in Blood Presence and the other in Frost Presence. 30 minutes is obviously not enough to remove the luck factor entirely, but all RPPM effects being significantly lower is more than enough to draw a conclusion.
PTR Blood Presence: 13.5M Fallen Zandalari, 5.3M Flurry of Xuen (13.7% uptime), 25.6% Feathers of Fury, 23.3% Cruelty - http://worldoflogs.com/reports/wxh5sb3mn4vmvoj6/
PTR Frost Presence: 8.5M Fallen Zandalari, 4.5M Flurry of Xuen (11.5% uptime), 23.2% Feathers of Fury, 15.5% Cruel - http://worldoflogs.com/reports/jo5gs17kh43tusj3/
Live Blood Presence: 29.8% Feathers of Fury, 72.7% Rampage - http://worldoflogs.com/reports/4wy99cwu6cap8dco/
Live Frost Presence: 19.4% Feathers of Fury, 66.9% Rampage - http://worldoflogs.com/reports/r93ydzfhq5d27sqf/
This pretty much confirmed what we suspected: The bug is not only real on Live, but has been affecting us from the start.
The implications of this are obvious: Runic Corruption becomes the default talent for any DPS DK since it now also carries a sizeable numbers boost. It's also been a definite contributing factor towards the gap between Unholy and Frost, given that Frost tends to default towards Blood Tap whilst Unholy (Festerblight especially) functions well with Runic Corruption's smoothness.
Mendenbarr's cooked up the exact numbers on Elitist Jerks if anyone is interested.
In addition, once the bug gets fixed in 5.4 (I am assuming you won't hotfix it since the tier is largely over), we'll likely need slight compensation for the DPS drop.
It would be great to get some information on what exactly causes the bug and how it will be resolved. Thanks!