"clearly hinders"

It was added to the rule book this year as a clarification and imo it did just the opposite as you seem to indicated.

Before, if the ball hit the batter in the area of the box then it was just play on assuming there was no intent.  If it was away from the box then it was an out because the runners are skilled enough to avoid the ball when its away from the box so failing to avoid would just be evidence of intent.

I would tend to use the same judgment today by placing a very high standard on "clearly" especially if the contact was only with the ball and not with the catcher.

But I haven't heard exactly what they are teaching on this now.

Baseball17...What you initially thought is the way to rule on this. There must be clear intent by the batter to deflect this pitched ball. Notice that I said pitched ball. It was not a batted ball. If it was, then the logic used on the field in your case may be true. This was a pitched ball that got away from the catcher. The batter, in doing what he should be doing, unintentionally touched the ball. That's nothing. Play on. BTW All codes.

Here's the rule as previously written:

It is interference by a batter or a runner when— 

(a)  After a third strike he hinders the catcher in his attempt to field the ball; 

The new wording:

(a) After a third strike he clearly hinders the catcher in his attempt to field the ball. Such batter-runner is out, the ball is dead, and all other runners return to the bases they occupied at the time of the pitch.
Rule 7.09(a) Comment: If the pitched ball deflects off the catcher or umpire and subsequently touches the batter-runner, it is not considered interference unless, in the judgment of the umpire, the batter-runner clearly hinders the catcher in his attempt to field the ball.

As described in the OP, it should not have been ruled interference.

Thanks gentlemen.  It is one of those things where I know just enough to be dangerous sometimes.  I just didn't believe in the circumstances, absent intent, that the ball should have been killed, batter out and runners returned.  Then I started reading more into the clearly hinders, and that is dangerous too.

Thanks