Over the last couple of patches, Malzahar was nerfed several times, while those nerfs were pretty severe. They weren't nerfs to the mana costs and CDs as we usually see to other dominant picks, but to damage ratios, which turned Malz from a AP carry into a stun bot.
I remember in one of the patch notes, where his ult was nerfed it said "Malz should need more than just his ult to kill an opponent". Are you guys even playing this game? If you ulted somebody naked (without E and no W), you were just wasting your ult, doing 20% of the enemy's HP at best and stunning yourself for 2,5 seconds.. It's the voidlings that kill the ulted target, not the ult itself.
Anyway, with the recent nerfs, I feel Malzahar has lost a lot of its "oomph", while his clear weakneses are still present. He is immobile short range mage (both his spells and his autos), his E now draws minion aggro, his early laning is garbage as it always was but now his mid and late game are that much weaker. The new items haven't exactly helped either, as Luden's doesnt really fit his playstyle, GLP without HP is redundant, as you have Rylais as the core kiting and slowing item and Archangels, while great, takes too long to come online in a world where games are often decided at minute 15. Not to mention a QSS exists in the game, which every player with a brain purchases against him - if you can't hold a target down for your voidlings, you aren't killing anyone.
Some sort of compensation buffs to his ratios - particulary R would be helpful, so his bad early game is properly balanced with his late game.
Also - point of discussion - is it time to talk about his voidlings? I'm not really a huge fan of his state that you are a basically a CC bot for your pets, so they can kill the target. Removing voidlings completely and just focusing on the Malzahar himself, funneling power into him in some other way - a new spell perhaps, is in my opinion the way to go. I wouldn't really mind the return of his Null Zone as his W, while the damage from his voidlings could be redistributed into his kit.
Voidlings aren't really the first thing that comes into people's minds when you talk about Malzahar - it is usually his Nether Grasps, his Malefic Visions ("Space aids") or his eternal silences and CC, so it's not like we are removing his iconic ability.
Anyway, some food for thought.