Old Raid Solo Nerf or just Bugs with Squish??

Maybe a month or so ago on the PVE 100 Server using only the provided gear (593 or so) I was able to easily solo Firelands 25m Heroic. Now in Build 18918 I tried it again ay level 100 with an item level of 638, 5p T17 Ret and took a lot more damage and my DPS was so low I could not get Beth'tilac down at all. Bug or did solo runs get hit hard with the nerf hammer???

Edit:
Dropped it to 10m Heroic since the instant save to 25m no longer happens:

Beth - Easily able to solo and bring to P3 before she went back down and the spiders would lock me up and I would die from aoe & poison spiders.

Shannox - would hit me with Go for the Throat, had to Divine Shield to break it and was able to kill him. It happens very fast into the fight and he didn't do it when I could solo 25m heroic.

Rhyolith - a Magma Flow hit me for just over 2m damage and one shot me. Killed him on the next try. With him constant turning on top of you and being so huge this is a problem because it makes it very hard to see things on the ground right under you and him.

Alysrazor - Took 3 feathers and did DPS in the sky. Had to get 3 more, but was able to kill her without any real trouble right before P2.

Baleroc - Crystal Damage and the nerf to self heals from it did me in, even with a Lay on Hands I was unable to keep up the heals and do enough DPS to kill him.

That's as far as I could go. I really hope this is just a numbers bug!