~のは…ぐらいのものだ => only (emphasis) N1
Limit
ものもV-ない => is not entirely impossible N4
Emphasize the negative meaning
ものの => but, although N2
ものの => but, although N2
Things do not match the prediction
...そのもの => Myself... N2
Demonstrate by example
ぐらいのものだ => Only A N1
(Not)only , (Not) even
たものではない => Impossible N2
Evaluate
...というのも => The reason is N2
Cause, reason
...もの (こと) も...ない => Leave it as is N3
Emphasize
そのものだ => exactly ~ N2
Consider it
... もの => thing... N3
Description
…ものとおもっていた => Thought it was... N2
Vague