His skills weren't hamstrung by having half of their power distributed to other fucking spells.
His pacing is completely controlled by his design and leaves nothing for the player, meaning you get stuck in a terrible spot, where either his kit does it's job, or it doesn't and you as the player of malzahar have basically no control if it works.
It feels like it's not you that got that S or S+ grade, just as much as it doesn't feel like it's your fault for literally being able to do nothing when your kit doesn't work.
Seriously even in their own description of their aim for the rework they had no fucking idea what they were doing.
"Here's some stuff we're less happy with and are actively trying to resolve:
A simple W>E>R is often enough to eliminate or remove enemies, leaving them little opportunity to act outside of not getting into his range.
...
Here's what I hope (these designs are still in progress) will be true of Malzahar following his changes:
Playing Malzahar still won't be a mechanically intense/exhausting experience."
( http://boards.na.leagueoflegends.com/en/c/developer-corner/6c2r0VAc-mid-year-mage-updates-malzahar-direction))
Seriously isn't this the definition of easy to play hard to master? He was easy to play if all you ever did was combo WER, but you were shooting yourself in the foot, in terms of potential, if that's all you ever did.
On the surface he was a easy assassination combo, though his play style beyond that surface level was extremely complex and by riot's own admission "intense and exhausting".