Having read both regularly I don't find this to be accurate. Groklaw makes actual predictions rarely and consequently has a cleaner track record. FM makes a lot of predictions and is, as you would expect, both wrong and right more because of it. He also covers a lot more cases.
As regards this case the big ticket item has been the Lindholm email and FM seems to have been right that it would stay in. And while I don't recall Groklaw definitively saying it wouldn't, their coverage certainly skewed heavily towards "remember that email from SCO that was just like this".