Experience is not just about your years playing football. It's also about the mental aspect, losing big games like cup finals and learning from those disappointments to form your character, along with learning how to deal with the pressure etc.
We've recently seen him awarded a MBE for his brilliant off-field work. I guess what I'm trying to say is, it's not about your number of years playing it's about your mental maturity that improves your all round game.
His physical age is 23, so when he reaches 27/28 his mental game will be at a much higher level than now. Most athletes will tell you the game is 80/90% mental and Rashford is already physically superior to Depay i.e Skill, pace etc. Conbining his mental aspect that's why I stated he has a higher ceiling than Depay.
Depay also went on record to say he wasn't mentally ready while at United, whereas Rashford at a similar age to him at the time has been our star player for a number of years.