Co-Workers With Alcohol/Drug Problems?

I work with someone who clearly has a alcohol problem. We will be, in back, doing stock and it's clear that he's wasted. He was sent home last week due to "being ill". I find it incredible that management doesn't realize what is going on? He's a much older guy who seems to take pride in the job and does pretty well. I'm just surprised that it's being handled this way. It's like the "pink elephant" in the room.