Depends what the lad wants doesn't it? Maybe he's happy down South. Maybe he saw a clearer path to the first team there. Vieira, while an unproven manager, is likely a draw to some younger players.
The point I am labouring towards is that we have no idea what goes on behind the scenes. We don't know we weren't in for him. If we weren't, we don't know there wasn't a very good reason for not being, etc.
And in response to @Tree13 - Time will tell if it's a missed opportunity. I am sure the forum will erupt with cryarsing if/when he scores or assists at any point this season, but there will be tumbleweeds if he is holding the Charlton scarf above his head in 3 years.
You're missing the point. It's not the PLAYER that is the missed opportunity, it is the combination of age, performance to date and price.
Let me try to explain my thinking.
WE need some wide attacking players - we agree on that, yes?
Option a) Olise. 19 years old, recent strong performances over the duration of a season in the Championship, £8m release clause.
Option b) Zaha. 29 years old, recent above-average season in the Prem, rumours of a fee anywhere between £40m and £70m.
(I freely admit there are other players in existence, I'm just trying to illustrate a point.)
If player a) fails with us after two years, he is still young enough ( at 21 or 22 ) that several other clubs will look at him and think "That was as much the club failing the player as it was the player failing the club. Just a bump in the road. He's worth a punt at £10m / £12m / £15m / whatever". In that scenario, we lose very little financially.
If player b) fails with us after two years, he's 30 or 31... he's a pace player (as are most in those wide attacking positions) and pace declines with age. The question asked by other clubs is "Was that just Everton using him poorly, or is he about to drop off a cliff? Ok, we can take a risk at a modest fee, or on loan, but that's it." In that scenario, we've spent £40m+ on someone who hasn't met the grade and we can't recoup anything close to the outlay.
Obviously if either player succeeds then brilliant, what a great purchase. And both MIGHT succeed.
The risk of financial loss in the event of failure, however, is far lower with player a).
EDIT: Given his age, you may well be accurate in saying the player preferred to stay down south. I cannot believe for one second that Palace was the only horse in the race.