The only nerf I think it needs is that the effect should be on the minion, not global. that is, I'd change the text to:
"Whenever you summon a minion, it becomes 5/5."
this allows tokens to keep getting the 5/5, allows the bounce/Charge combos, but it adds some options for removal and silence. As it stands, almost all removal has no effect. Which means you have to either tech for this deck (at the expense of basically everything else) or plan to lose to it in a hopeless and frustrating fashion.
That said, this deck seems to be a plague only in around the 14-20 range. Last month I rarely saw it in the 10-12 range (that's as far as I got) and I'm at 13 now and rarely see it.