Not only was 1966 his final year of volume scoring, but it was his only year playing in a stable environment as a scorer with the 16 foot lane. Even if the wider paint took him a couple feet further from the hoop, it helped him out too a lot since there was more room in the paint to work with not only for himself but the entire team as well, mainly cutters. This is especially true given how poor the concepts of floor spacing were back then compared to now. If he played with the 16 foot lane for the first five years of his career, I'm sure his team's offensive results would be much higher on average. Look how poor the spacing is on this play for instance:
https://www.youtube.com/watch?v=XNw0c19DhIU&t=13m48s
A wider paint would reduce the defensive congestion by default. The only way to ignore Wilt's offensive impact on the 76ers is to assume that a 22 year old rookie Billy Cunningham was basically a +6 player on offense the instant he arrived. For comparison, as a rookie in 1960, Wilt improved the Warriors by +4.1 (+3.3 on offense) from the previous year. Even Oscar only improved the Royals offense by +0.8 as a rookie. The issue with Wilt was not flat out incompetence as many here have suggested, but rather inconsistency, much of which has to do with the constant changing of coaches, players, and the narrowed lane until 1965. And of course his inconsistent FT shooting.
Royals ORtg
1960: 89.2 (+1.6)
1961: 94.8 (+2.4) *Oscar first season, offense improves by +0.8
1962: 98.8 (+4.5)
1963: 99.0 (+3.4)
1964: 97.6 (+3.9)
1965: 97.3 (+4.2)
1966: 98.2 (+5.1)
1967: 98.9 (+1.6)
1968: 101.1 (+3.4) *Oscar missed 17 games
1969: 100.1 (+4.0)
1970: 99.2 (-0.9) *Cousy takes over
Lakers ORtg
1958: 84.6 (-1.2)
1959: 87.4 (-0.2) *Elgin first season
1960: 86.3 (-4.4)
1961: 90.8 (-1.6) *West first season
1962: 95.5 (+1.2)
1963: 97.4 (+1.8)
1964: 95.9 (+2.2)
1965: 96.4 (+3.3)
1966: 98.8 (+5.7)
1967: 99.1 (+1.8) *West misses 16 games
1968: 102.9 (+5.2) *West misses 31 games
