I am already detecting the errors ATP made with the 1973 'official' rankings.
1. John Newcombe didn't play 17 tournaments, but rather 16. One could count Johannesburg-2 because of confusion with the main south african event. But they are not the same, Johannesburg-2 was a played-once totally different tournament played among a few South African other events. It was part of a SA Circuit they were trying to make, and was never part of either GP or WCT. To prove this is correct, when you count John Alexander's total tournaments, you get 29 if you take this event into account. Yet, his official count stated 28. So, John Newcombe played only 16 events.
2. Stan Smith seems to have only played 23 events, despite his total being 24. This must be further verified, but it is likely it's another error. If this will be true, it may change Stan's YE ranking.
3. Metreveli, Ross Case and a few others also have more tournaments in their divisor than official tournaments actually played.
4. Nastase was able to count 23 tournaments thanks to the ex-GP, ex-WCT rule. Rule by which John Newcombe also gets to 16 (not 17 because Johannesburg-2 was already eliminated). His 16 also comprises of ex-WCT event Las Vegas, which, if out, would take him to 15. But if this rule is enforced, Jimmy Connors should have 18, since he played both Salisbury and Hampton, just like Nastase. Another contradiction which fuels the certainty that this rule actually existed and any tournament not part of it, was not considered official. With one exception. Since most of the tournaments used to be part of the GP, the European Spring Circuit was counted entirely (Valencia and Florence included).
5. It was contested that first round Walkovers would not result into the tournament being counted. I have found sufficient evidence to say that this is wrong. They did count. In 1973.
More to come.