I agree with Jols when he says technic and skills are often overrated by players (especially the young ones).
I am not a great player, and don't have amazing tricks, but as I used to say to the youngsters I trained: if everybody in the team can properly give a pass, receive one and swim like hell, you can already win quit a lot of games.

Furthermore it's up to players to take responsibilities. Every players should assure their endurance is optimal, especially when you have a long tournament. This requires a lot of long distance swimming, running, cycling or even rowing. But don't use the precious time you've got in the pool with the team for that. This is something players can easily do on their own time.
Pool time should be used for sprints, basic skils and lots of collectif play and strategy.

Whether players are ready to do so, of course depends on the level and ambition of the team.