What happens if you knock the bails off while the batter is behind his crease?

Question

For example, a batter steps forward as he attempts to hit the ball. He misses, but is out of the crease. He quickly turns back and gets his bat over the line just before the wicket keeper knocks the bails off.

Does it make any difference to the score or game?

Just curious as I'm watching a game and this happened, but the wicket keeper stopped just before he knocked the bails off. I'm wondering why he didn't knock the bails off anyway, just in case?

Edit: and a follow up question to this. If it's not against the rules, what stops the wicket keeper just doing this randomly to waste time or for some other reason?

Answer 1

Does it make any difference to the score or game?

No. The batsman was in their ground, so they are not out.

I'm wondering why he didn't knock the bails off anyway, just in case?

Primarily, because doing so would at best (see below) be against the spirit of the game, the same as appealing on every ball even if it's blatantly not out would be.

There's also the issue that while it is possible to put the wicket down when the bails have already been removed, it's much harder than when the bails are there. If after getting their bat down the batsman was careless enough to lift their bat without making their ground with at least one of their feet, the wicket-keeper would easily be able to dismiss the batsman if the bails were still on; if the bails were already off, and the stumps otherwise disturbed, it would be harder for them to do so.

what stops the wicket keeper just doing this randomly to waste time

Because wasting time is itself against the laws, specifically Law 41.9:

41.9.1 It is unfair for any fielder to waste time.

and if repeated will lead to penalty runs being given to the batting side.