Junk is the best pay to play defenders and power hitters. Both styles are rhythm players who love consistent speed and spin, and both have come to dominate the top of the rankings in the last 10 years thanks to the tour being 90% clay and slowing hardcourts.
It was natural that the best of the next generation would develop into junkballers as a method of challenging them.
but murray is a junky player himself insin't he? He gets roasted by Nadal
Murray is more defensive than junky when he plays someone like Nadal, it's a psychological thing. But he has the potential, which is why people talk about the top 4 rather than the top 3.