They failed because the reason for writing was completely wrong.

This isn't completely wrong, but there are three problems with it.

"Even though I feel what you did was completely wrong."

Is that the case or have I got it completely wrong?

And so what if he was completely wrong for his previous position?

It changes your life when you meet someone completely wrong.

And in fact not there, but to a completely wrong farm.

There is a sense in which students cannot be completely wrong.

That would have been completely wrong, in the context of the book.

That's only a guess and it may be completely wrong.