I don't have scientific data to understand exactly what is going on here. But I do see that Frenzy buffs are not happening hardly at all.
I did Durumu Normal 10man last night (5.3) and on Monday (5.2). I always try to do it as BM. I went from 66 frenzy stacks in 5.2 to SEVEN frenzy stacks in 5.3. Details below.
On Monday my pet had 163 melee attacks and 72 bite attacks. I was using a boar. The fight lasted 8m39sec. This resulted in 66 frenzy buffs with a total uptime of 89.3%. I hit focus fire 10 times and got 270 focus total. This is pretty good.
Last night, my pet had 155 melee attacks and only 8 claw attacks. I was using a spirit beast. The fight lasted 7m27sec. This resulted in only 7 frenzy buffs with a total uptime of 13.6%. One time I saw it stack to two and hit focus fire (once) and got back 12 focus. Once.
Yes, I had a few variables different in the fight. Different pet. Different raid (3 heals vs 2 heals). But both pets had full autocasts on except for Growl. I had the same talent choices. aMoCs and Glaive Toss. So no Dire Beast(s) talents were in play. I also spent 3k valor on upgrading gear. I reforged and stayed hit and expertise capped.
Monday's 5.2 worldoflogs.
Wednesday's 5.3 worldoflogs.
I've added to a Blizzard bug thread on the issue. Check your logs!