This is just getting stupid.
If it is so easy to have to good strikers that both deliver goals without playing together, why is there hardly any team in world football that choose to do that? Why should that work out fine for Moyes now when it never has in his 25 years in management?
Dobvyk and Sørloth where a year younger last summer. Both of them.
Resell value is important, but just as important as age is what you paid for them and what you are paying them. You'd expect Barry to be on very modest salary in Villareal and that is the most important reason for him to give up life in Spain and Champions League football for a struggling Premier League team that plays awful defensive football.
But what if Barry fails at Everton? What is he doesn't get starts after having been signed for £30 million and tripled his wages. What is the market for him in 18 or 24 months? If he doesn't start for Everton, no one in England will buy him. And outside of England there are only a handful of teams that are willing to pay +£20 million and offer Premier League wages to players. If he's good enough for these teams, he's one of Evertons best players.
If resell value is important, you play your most expensive players. One season for Barry as backup for Beto and there's hardly any value left.
Manchester United thought they were smart when they signed Højlund. Young. Resell value. Two years later they can't get rid of him. They'll end up sending him on loan or to sell him for half of what they paid for him. He is younger than Barry, much better and he has played 95 matches in two seasons.