Where do you scale Sasori?

I’m personally very confused about his scaling.

Statement wise:

He killed the 3rd Kazekage, destroyed a nation and Deidara says Sasori is probably stronger than himself. Then Kisame goes on to mention that Deidara is one of the stronger members.

Feats wise:

Sasori gets reacted to by Chunin Sakura and damaged by her even without Chiyos help. He also himself mentions his performance is embarrassing against a girl and an old hag.