With just dev on and no recalc, a lot of it will depend on your TCR setting. The higher it is, the more volatility of player performance.
That said, I would think it's less likely of a 35-yo than "younger" players, which is kind of how it works IRL.
One factor of the game remains - even if there is improvement in a veteran player, it won't be reflected in a differential between OVR and POT, which freezes at 30 as far as I'm aware.
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