I did some Sim manipulation to see how these buffs should translate. Basically, I just did multiple sims assuming both single target and AoE and added 15% to the abilities that are getting buffed. Used my 226 ilvl BM Hunter.
The results were about 6.2% overall increase on single target and 4.8% overall on AoE.
Not to be a naysayer, but this just seems like the 5% aura buff we got in 9.0, but targeted to specific abilities to make it sound like a bigger buff. It’s welcome, but still a lazy response in my opinion.
As far as how much that will help us…
My BM Hunter is 226 item level with all of Shadowlands to pick and choose gear from the vault to optimize stats.
My Shadow Priest is 222 item level after three weeks of life with whatever gear I could throw together.
Shadow Priest still sims 3-7% ahead of my Hunter with the SP nerf and BM buff taken into account. I think this buff will move us up from the bottom, but doubt it goes higher than middle of the rankings.