If ex straight hat allowed buzz saw to follow up with a combo on a grounded opponent it would be all he needs imo.
Honestly I think a 3% buff to those grounded combos and a 1% buff to his projectiles would be enough. This should be completely possible by reducing the scaling on his regular spin. This shouldnt affect tempest because the regular spin isnt the same. The scaling on tempest spin and the buzzsaw/hat trick spin work the same now, but they should be able to change that without changing tempest spin. Making buzzsaw more dependant on meter will force you to play less buzzsaw-like. His meter should be used for b321combos ex low hat and ex hat setups, ex low hat after 112124, occassional spins after low hat on block to keep your opponent honest and b22 in the corner.
The damage on his combos with 21 ender would be:
11212 spin = 27% midscreen, 31% in the corner
b22 spin = corner 31%
F23 spin = midscreen 28%, 32% in the corner
This is the best solution imo for buzz saw and I have mained him since launch.
BTW the tempest nerfs would be completely fine imo if buzzsaw and hat trick would get some stuff in return. They are fine right now, but the damage nerf wasnt needed if they decided to nerf ex hat spin and jump 2 anyway.