Reason of  conducting a league

I believe your question is about the various domestic cricket leagues that are played within a country / state.

The main purpose is obviously to nurture talent at the root level and create a talent pool available for the selection of the national team.

The players from the national team occasionally play in some of the league matches. This helps the junior players to learn from the seniors. Also this helps, the out-of-form national players to get a few games to work on their technique and form.

The seniors players who are recuperating from an injury, use the league games to improve their confidence and prove to the selection committee, before playing again at the highest level.

However, in the past 8 years, ever since the prominent raise of T20, the leagues have take a different leap.

Almost, every major cricket playing nation hosts a T20 League, once in a calendar year. The calendar has been planned in understanding with the various country cricketing boards, so that the international ‘star’ players will be available to play for their country’s league.

This arrangement, brings in a huge revenue to the game, it’s sponsors and the players equally. Viewers also get to see the international star players play along side their national players and are guaranteed entertainment . The local young talents get to play with the international players from different countries, which otherwise would not have been possible, unless they were selected in the national team. The younger players can improve their skills, get guidance from the senior players, showcase their talent to be selected for the national team. Or simply the player’s value goes up in the next year league, since the selection is based on auction.

So overall its a win-win for all the parties involved.

In India especially, the success of National T20 league (IPL) has been so huge that various states have been replicating the similar formula by conducting various state level league tournaments.