Shredder has pretty much become a plague. Yeah, we get it, its "fun". But at this point most people have seen every possible result go their way or the other guy's. From Millhouse and Succubus to Explosive Sheep, Doomsayer or Unstable Ghoul. Its not even a happy or maddening surprise anymore as just a sigh and a muttered fuck this shit or an oh well I won that time. So the novelty is gone, but the card dominates their design space options in the four slot. The last couple sets every review of every four cost card is pretty much "well, you don't want to cut shredder for it though". Combine that with the fact that most classes already have very high quality four slot options (too many to even list, just look) and we are stuck with no neutral four drop having a fucking chance against this one minion.
In general they painted themselves into a corner with Naxx and GvG and now they are paying for it. They seem to have tried to avoid this power level problem in BRM, TGT and LoE but it leaves the whole field stagnant since they are afraid to make anything too good again but nothing can compare to their past mistakes. Shredder, Mad Sci, Loatheb, Belcher, Boom. And then there's class ones from those expansions, Minibot anyone? Blastmage and mechmage is STILL viable with no real update to it. They've struggled to make any neutrals that can ever compete with these cards and its bad for the game. Maybe I'm overreacting, IDK.