Asimov? story I'm trying to remember

[jrbl]

I seem to recall a science fiction story in which this research team is trying to build something fantastic. They're hindered, though, by not realizing that the engineer who just retired was the very reason they were ever able to get anything done. Nobody much understood what he did, so they let him go. But it turns out that what he did was walk around, drinking coffee and talking to people. And that that was actually the thing that enabled them to get anything done.

Unless I made it up.

Does anyone have any idea what I'm talking about?

(In my head it was written by Isaac Asimov, and it would be true to form. But I really have no idea.)