[lurker] And if after the merger, the best players from that team merged with the best players from CESA, it would be even better. [...]

This is known as the "slippery slope" logical fallacy, in particular what is known as the "causal version" of this fallacy. This type is based upon the claim that a controversial type of action will lead inevitably to some admittedly bad type of action. It is the slide from A to Z via the intermediate steps B through Y that is the "slope", and the smallness of each step that makes it "slippery." [Source: Fallacy Files.]

I prefer the following argument to make your case: if the best players in a specific age bracket and gender cared enough to play on a single team, then there is nothing stopping them from all talking to each other and trying out for that single team. Until this begins to consistently occur, there is apparently little demand for mergers to occur.