The most "correct" way of updating state?

So I was trying to further refactor the Scoreboard component and started to think about the most "correct" way of modifying state. Now I know that what we currently have works perfectly fine but I've stumbled upon those 2 things in React docs:

https://facebook.github.io/react/docs/state-and-lifecycle.html#state-updates-may-be-asynchronous

https://facebook.github.io/react/docs/state-and-lifecycle.html#state-updates-are-merged

Taking that into account, I've changed the onScoreChange method from:

  this.state.players[index].score += delta;
  this.setState(this.state);

to:

  this.setState((prevState => {
      players: {
        score: prevState.players[index].score += delta
      }
  }));

From what I understand, this approach not only makes the updates 100% predictable (considering the async way of state updates) but also makes us merge only the exact part of the state object that we need to merge, which comes in handy if our state object grows in size. It also looks pretty hip.

Now first of all I'd love to know whether what I've done here would in fact be the "correct" way of doing things at the moment. Whether answer to that is yes or no, I'd love to know what would be the best, most correct, futureproof, ES2020 and bleeding edge way of modifying component's state based on props and its previous state.