Same as i was saying the other day mate, depends what metrics you are using to determine a players peak age, so many variables that a single study with set parameters and a small time frame can't possibly produce a definitive answer.
Will give you examples why, do they take into account how long the player has been playing/training at the top level - number of games - miles on his clock etc?
Do they take into account age cross indexed with injury histories to show how a player whose not suffered with any significant injury will tend to age much better?
Do they take into account how professional the player is, for example Ronaldo current one compared to Brazilian Rondaldo?
The person you quoted said about players relying on pace as their main attribute and he can't think of any who was still at his peak post 30.
Can give one straight away, Vardy is 31 - still absolutely as fast as he ever was.
Won't argue that pace declines with age - only have to check sprinters and world records for that obvious fact, but will throw out another stat to balance that, longer distance runners tend to become better as they age, similar parallels can be said about footballers, Giggs who he stated etc - his best season for United was when he was 30, and arguably his greatest ever game was then too against Juventus, Similarly Ronaldo has become a slower BUT better player at 30 than he was at 25 (his supposed peak age).
It's far too wide a subject to give a definitive answer on