There were several changes to bosses with the last patch, here are the ones that I could find commented on by Blizzard staff on the forums.

Malguar changes - Tigole

Malgaur did get a slight nerf. His overall damage is still the same but he now attacks faster but hits for less. This should result in less spikey deaths. It's a pretty subtle change and will be mostly noticed by undergeared raids.

Lurker Changes by Daelo

We've just deployed a pair of hotfixes that affect the Lurker Below encounter in Serpentshrine Cavern.

- Coilfang Ambushers may no longer be charmed.
- Lurker Below should no longer emerge from under the water prematurely.

We're also looking into the problem where the Lurker's primary melee target gets knocked back by Geyser even if that player is not the actual target of Geyser. I currently have no ETA on a fix for that issue.

Gruul Changes by Daelo

We've now deployed a hotfix that fixes the targeting of Gruul Hurtful Strike. The ability should now hit the second person on the threat list, and not the third.