Decade stats are worthless. Winning a slam 15 years apart could either count as 2 decades or 3. While another player might defend his title, but because it happened at the turn of the decade, it counts as "won in 2 decades.
Longest span between first/last title is a much better stat.
One of my favorite aspects of the goat race is ttw posters who admit homogenization / inflation, yet proceed to make apples to apples comparisons to past eras.
The "Joker v Borg Wimbledon resume" thread being a great example.