I think Ameer's play is being amplified by circumstances, and perhaps a bit of recency bias.
Without question he's showing he belongs in the conversation about Nebraska's very best at I-Back. But was he better than Ahman Green? Mike Rozier? Lawrence Phillips? Nope, and with Rozier & Phillips, maybe not even close. But I'd put him, right now, on par with Green.
With a better O Line, I'm not sure we would see a "better" Abdullah, for the simple fact that Ahman Green didn't have to juke, jump & jive his way through defenders like Ameer has. The Pipeline was so good they just blew huge holes in the defensive line, and Green didn't have to make a move on someone until the defensive backfield (often - not always). We're seeing moves out of Ameer out of sheer necessity, just like we did with Rex, who often turned two-yard losses into three-yard gains.