The term stroke mechanics we mean the movements of the human body and bat.
You have already heard this statement: Simple mechanics are better and more efficient.
Coaches often justify this statement with this: the easier, shorter and more compact movement is better for players in terms of time. When these coaches comment mechanics of the professional players they said: They're doing less movements than other players and their swings are very simple. These coaches are working with students during the lesson to restriction of the movements majority of the time.
But is this the right way to improve? If professional players would make a few simple moves in their swings, sports like table tennis would be taught during some weeks or perhaps a months. They would learn one of the few moves of professional players every day, and they should have identical swing like them.