HELP: Does a player's age matter?

Hey there. Just wanted to ask: if, for example, I take Kobe Bryant and change his birthyear to, let's say, 1933. That turns him into an 80-year-old grandpa. So, if ever you do something like that to a player, will it matter? Do a players' ages have anything to do with their performances in-game or is that just a piece of numerical data? Just asking.

Hahaha
another question that is funny for me
i tried Jrue Holiday with the birth year "1"
nothing happend really
just looks funny. (The Age not the Apperance)

Let's just assume that nothing happens, then. But I need more answers, just to be sure.

make the player older and they will retire sooner, and making them younger gives them more time to develop and potentially get better ratings.
but you can usually only tell by playing association and watching the long term effects over multiple seasons

According to the REDitor blog for this year's version, there's two parameters in the roster, "Peak Age Start" and "Peak Age End". What this does, I presume, is determine up to what age a player keeps developing while in Association, and from what age on they'll start to deteriorate. So changing a player's birth year will definitely affect their progression at the end of the season.

I see. How is it then that for some players (on the legends teams), the year doesn't show up on the Edit Player screen? It just shows something like ----.