At HW 11 of the boxrec top 20 are age 34 or above. Only 3 are age 27 or below. None or under 24 At LHW 6 of the boxrec top 10 are age 35 or above. 4 are age 39 or above At LMW only 2 of the boxrec top 10 are below 30 years. The top 3 are above 35. I don't think you could have had these kind of numbers in the past.
Its normal because fighters on top of their game are more inactive than they used to be, therefore it takes them more time to move up the rankings.