[LRZ]

So you say. But if FED does not require a quality throw, what does it matter that the throw was "errant"? Could the first baseman have had a play on catching the ball? The BR is in foul territory yet not in the running lane. If he's not in the running lane and if he were hit by the throw and that prevented the first baseman from catching the ball, how is that not a RLV?

Was the BR in the running lane? No.
Was the throw "errant"? Yes.
Is a quality throw required in FED? No.
Did the BR interfere with the fielder receiving the throw? Yes.

In FED terms,
Was the BR outside the three-foot running lane? Yes
Was he doing so while the ball was being fielded or thrown to first base? Yes.

It is an official ruling, but perfectly rational? Either facts are left out or are unclear--what exactly does "errant" mean here? how far off base?--or the ruling itself is not supported by the rule itself.

But I'm open to the suggestion that I'm missing something. If I am, please point it out--a conclusory statement does not show me my error.