I dont think the idea is to only have young and hungry players though. They need players to learn from and who will perform at a certain level while they improve, become more consistent and learn the habits of a quality player.
I think Mandzukic would be okay and a short term option who would obviously improve us, filling in for Martial or providing an alternative to him when we look for a plan B. But the story is about a £73 million budget for a striker and thats obviously not Mandzukic.
A couple of seasons scoring around 10 goals in 20-25 league appearances including subs while Greenwood still gets gametime and chances, but has time to improve and become less green would seem reasonable to me. But then there probably isnt room for this £73 million striker