I am not sure what you are looking for but Marcelo Rios never won a GS and still became No. 1. The biggest tournament he ever won was Indian Wells.
Also Becker won Wimbledon, US Open and Paris Bercy in 1989, reached the semis in RG and the WTF final yet never became No. 1 that year while Lendl finished 1st.
sure, let's take 2 outliers, and based on 2 outliers thrash the system.
for a moment, 31 years passed since 1989
US, the biggest democracy as it presents itself to the world, had chosen a president who got less votes than the opponent, and for some weird reason they didn't thrash their system, but ATP shall do so
now, on Lendl 1989.
It's so convenient to ignore that Lendl won AO in 1989, had some other solid results, including winning Key Biscayne, that had a main draw of 128 players, where Lendl ranked as #1 had to play the R1 (R128).
In the Sunshine double these days, the seeded players skip R1. Lendl had to play.
Then Lendl reached the final of Wimbledon and USO.
Beside AO and Key Biscayne, he won Scottsdale, Forest Hills, Hamburg, Queens, Montreal, Bordeaux, Sydney 2, Stockholm,
Lendl finished the year with 10 titles.
so, perhaps he wasn't a journeyman.
and perhaps this was one of the reasons to change the points distribution, where GS and Masters 1000 count heavier as opposed to 500 and 250 events, don't you think so?
so, what is the relevance of 1989 in the context of discussing performance of Fededer, Nadal and Djokovic? I don't know.
please help.
so the only huge exception is Rios, who got to #1 with 1 GS final in the context of past 52 weeks, but winning 3 M1000 events and some smaller events.
so, based on this you want to thrash the entire ranking system?
dude, go chech some of the GS draws, all of the Big 3 had some draws that are considered 250 event level on this board.
if something, there would be much more evidence that it is much more likely to win a GS tournament with a lucky draw, then getting to #1 because of weak results.