If that's what you think, you're way off base.

你如果那么想就全错了。

“Williamson is way off base,” says Mr. Miller.

“威廉森做得有些离谱。” 米勒先生说。

So far as I know, what he said at the meeting is off base.

据我所知，他在会上讲的话是与事实不符。

The report was well written, but it was slightly off base.

这篇报告文笔不错，但是立意错了。

The report was well written , but it was slightly off base .

这篇报告的文笔不错，但是立意错了。