Just experienced this myself. Recently picked up my 370z with 050's only 6kmiles & 6-7mm of tread all round, found the car very twitchy & slippery in the wet, got the geo tweaked a little but still no good so put a fresh set of MPSS's & the car drives great,
What I have found with the 050's is that they are a great dry weather tyre, they don't over heat on track (unless drifting) but in the wet when they break traction near enough all the grip/purchase on the road is lost. (Octet also found this in Wales earlier in the year )
But the MPSS's are on another level the grip levels in the dry are 2nd to R888's. In the wet they offer an extensive amount of grip, when they break traction they still give a decent amount of purchase on the road. These therefore give a huge advantage over the 050's in the wet as you don't run scared of the car rotating on change of surfaces or white lines