You don't need to be fit to be a skillful cricketer, and you don't need to be skillful cricketer to be fit. But, both elements together will feed off each other to make you a better player.
That's what this diagram illustrates.
Of course, the above is an over-simplification to make a point (that fitness is as important as skill), and there are a lot more layers to it.
For example, the type of "fitness" work makes a huge difference. Bodybuilding and jogging is less effective than strength training and mobility work.
The same applies on the skills side. You can roll your arm over in nets for hours and never improve. On the other hand, you can perform drills, bowl to targets and work on handling pressure.
However, the basic principle still applies: To be the best cricketer you can be you need to be an athlete. That means smart skill work and smart fitness work.