They look more like gravel rally tyres looking at that tread!
Interestingly Yoko describe them as a 'street sport tyre' rather than the 48s which are a 'semi slick tyre'. Looking at their website I'd suggest they're leaving the 48s for the smaller track-focused cars (Caterhams etc) and the 52s are for more general-use larger cars. Certainly with the grooved bands all the way round they look more like a regular tyre and far more usable in the wet than than the 48/888 style tyres which were always a bit squiffy. I wouldn't be surprised to see the 52s coming in 19" and 20" sizes too, to try and compete with the MPSC2.
Agree, they are an A rating for the wet and larger sizes are due before the end of 2017.