The thing is with Harper, he's pretty much always been Premiership quality since about 1999/2000. Just people always compared him to Given, and whilst Harper isn't as good as shot-stopper (which seems to be the only criteria for a good goalkeeper according to some people) he's far better on crosses and commanding his box, and his kicking/distribution is arguably better. He's still a decent shot-stopper anyway, but always came under fire because he never seemed to make many "heroic" saves like Given did.
I agree with Ronaldo in that he's still good enough for the Premiership right now. He's a good solid keeper.