In the loop

In the loop: informado, por dentro ciente (dentro de um grupo determinado)

“Keep me in the loop.”= Mantenha-me informado.

I don't know what's going on with the Jones deal since I'm not in the loop. =  …com Jones, uma vez que não estou por dentro das coisas.

Bob and Jean are in the loop. They can tell you what's happening.= Bon e Jean estão bem informados. Eles podem…( www.thefreedictionary.com)

In the know

In the know: informado / que sabe das coisa / saber das coisas mais do que a maioria das pessoas

“Let's ask Bob. He's in the know.

“I have no knowledge of how to work this machine. I think I can get myself in the know very quickly though.”

 “People in the know go there for the best skiing in the east.” (www.thefreedicionary.com)

On the ball

On the ball: informado, instruído, competente, 'por dentro', alerta

If you were on the ball, this wouldn't have happened. ( www.thefreedictionary.com)