I guess I should just post it here instead of making a new thread.
MAJOR CHANGES EXPLAINED:
Azmodan: People figured out how to play him. Stacking Q build. It's OP in every team comp. Almost undodgeable Nova ultimates every 10 seconds is ridiculous to deal with. Can't be bursted either with his high health pool + healing meta. Just sucks on certain maps (Sky Temple & Haunted Mines)
Illidan: Brightwing double poly not a threat & multiple healer meta change is great for Illidan. Illidan is strong when he has healers backing him up because he becomes insanely tanky and can just run down carries (also why ranged DPS have gone down on value) and is strong against healers because he does better in sustained fights and when the enemy team lacks the damage to kill him instantly. Tankiest character in the game if played properly. He has, and always has had, the ability to soak a ton of damage and still stay alive through proper use of E, metamorphosis, blood for blood, and first aid. Stacking healers on top of it just makes it more ridiculous.
Rehgar: Healing ward change + double healers = you can't burst rehgar because the other healer will keep rehgar alive so he can ancestral. People also finally figuring out how game changing a good ancestral can be.
Uther: Always been good, even better with the meta change to running multiple healers and having his main counter (brightwing) nerfed.
ETC: Arthas nerfs, Stitches somewhat out of meta, goes along well with the healer/melee assassin meta.
Jaina: Her proper build finally getting figured out. A good Jaina player can zone all the carries on the enemy team by herself. High burst damage + play-making ability. Our team's Jaina player made a montage for fun recently and it has some great clips showing Jaina's potential: https://www.youtube.com/watch?v=ejvaxkvM6fE
Malfurion: People found out stacking healers is OP + brightwing nerfs.
Sonya: Best initiation in game along with high burst damage + tanks, especially arthas, getting nerfed means Sonya dominates the frontlines now.
Tassadar: Essentially a third healer with the ability to zone out enemy carries (Valla, Tychus) Healing ward + shield also adds a ton to the effectiveness of double healer as well as to Illidan's ability to dive.
Kerrigan: All the current Tier 1 heroes ruin Kerrigan and her loss of rewind hurts. Still very useable in certain situations.
Stitches: Hooks seemingly don't matter when the enemy team has so many healers to burst heal your hook + the enemy team instantly dives you with Sonya, Illidan, Kerrigan, etc. Nerfs also hurt a lot.
Tychus/Valla: The two top tier damage carries have fallen out of flavor because they lack the burst damage to beat multiple healers + they're extremely weak to getting dived on by Sonya, Illidan, Jaina, E.T.C., etc.
Brightwing: Nerfs and lacks the massive healing other top tier supports have to survive in the meta. Her only real use now is for emerald wind to try and counter dive comps.
Arthas: Loss of envenom means Arthas can't threaten your carries. Ghoul nerfs means he can actually be kited and run over. E range nerfs means Arthas can't walk + autoattack people down.
The overall meta seems to be shifting towards stacking healers, stacking melee assassins, and a ranged damage (preferably Azmodan / Nazeebo) Stacking healers makes your melee assassins unkillable, they also make each other unkillable. your melee assassins can destroy their ranged carries in a few seconds as Azmodan/Nazeebo have great follow up damage for any initates.