I think Sona Ping means that it is impossible to calculate it's ''true'' efficiency if you take no numbers into account.
Let's say you take a random sample of 3 5v5 matches. Each match has an entirely different set of champions with different runes and masteries for every champion from those 3 matches, but we don't know who those champions are or their stats.
Let's say that the Abyssal Scepter is always 103.09% gold efficient regardless of numbers. It is 103.09% gold efficient according to the LoL Wiki without it's passive.
Match 1 - We don't know the champions or their builds so we assume Abyssal Scepter is 103.09% gold efficient in this match.
Match 2 - We don't know the champions or their builds so we assume Abyssal Scepter is 103.09% gold efficient in this match.
Match 3 - We don't know the champions or their builds so we assume Abyssal Scepter is 103.09% gold efficient in this match.
Since we have no numbers, we can't tell how efficient it really was those 3 matches so we have to use the information that we do know which is the Abyssal Scepter's gold efficiency which is 103.09%. It is impossible to tell how gold efficient the item REALLY was those 3 matches because we don't know the champions, their masteries, runes, or their build so we assume it's base efficiency.
If we DID know what the champions and their assets were, we would be able to do a calculation and find out how truly efficient it was each match.
It could be 110% gold efficient in Match 1 or it could be 120% gold efficient in Match 1, but we don't know what was in that match so it is impossible to tell it's true efficiency.