Jay has more than a few albums where half the beats are just ok or mediocre. I named them earlier in the thread. We can go into that more in depth if you want. And for every dope Swizz or Timbo beat he's had you can point to an unspectacular Swizz or Timbo beat also. Jay just doesn't get criticized as harshly for picking bad beats as Nas does. No MC does.
A lot of what Timbaland has done for Jay is classic though. He gave Jay top shelf production on the Vol. 2 and 3. The Blueprint albums is where the chemistry was off and they had mediocre to wack songs. They rebounded with "Dirt Off Your Shoulder". MCHG was hit and miss.
Why are we focusing on Jay Z? He doesn't get criticized as harshly because Jay Z's fans didn't box him into one particular set of producers. Nas gets criticized because he has fans that complain when he moves outside of the box they've put him in. So when he has fans that are doing it, haters are going to amplify those critiques and complaints to support their narratives and agendas.