Could a mid table championship team beat Rosenborg away OR Wolfsburg or handle Man City? I still find people's perception of that league wierd. In fact if they played Everton they'd probably win. The last time they did play us was a pre season friendly I went to and they won comfortably.
Otherwise I agree with you,
Yes, on their day, they could. I'm not saying Celtic are a bad side, but like most others, I just dont think they would compete with the big boys in the Prem League.