How often do you smart coaches use them?

What might a few instances be where it might seem like a smart idea to use a doubleteam when actually it's not?

When has a doubleteam made the difference in you winning a close game?

I'm not a smart coach, but I can testify that using a double team on a star player on an otherwise poor team can be a difference maker. But it can also backfire on you if the star is so good and just rips your double team for foul after foul.

I used it a lot in my first season and got burned too much even though it helped reduce the targets output, but that output was more than made up for by open players as a result.

You can tell using the PbP how effective it is in the game flow, because double team effects are often specifically referenced in the play descriptions.