Its pretty hard on this game to improve your created players stats, as in it takes forever to build up enough experience with your players being so poor.
So here's a tip:
Go on 'Double Wicket' and make it the maximum overs. Then chose your two created players and put them against two very poor bowlers. This way you can slog it all over the place as the bowlers stats are poor, and every time you do get out it doesn't affect your score. In a normal game, that would be the end and you wouldn't have much experience.
You should be able to get a century each off 10 overs, if not more.