How is 1 RBI, 2 run single possible without any errors?

Question

Two are out, runners on 2nd and 3rd. Batter hits a ground ball to 3rd baseman, he throws the ball wide to 1st, forcing 1st baseman to take couple of steps off the base to reach it. As a result batter runner is safe on first and runner from 3rd scores. 1st baseman then throws to catcher, but he's slightly too late and runner from 2nd slides in to score.

I'd have scored it as an error on the 3rd baseman... so no hit, no RBIs, no earned runs.

Official scorer however scored it in a manner I don't understand:

[batter] singles to third base. [runner from 3rd] scores. [runner from 2nd] to 3rd. [runner from 2nd] scores on throw. 1 RBI.

Batter scored a base hit, but only one RBI, however pitcher was scored with 2 ERs. No errors were scored for the defensive team. How is that possible?

I understand the no-error call, you could say it was a tricky throw, but if the throw from 3rd was good, and throw from 1st was good, why only one RBI? What does "scores on throw" mean?

Only relevant rules section I found that might apply here is 9.04c:

The Official Scorer’s judgment must determine whether a run batted in shall be credited for a run that scores when a fielder holds the ball or throws to a wrong base. Ordinarily, if the runner keeps going, the Official Scorer should credit a run batted in; if the runner stops and takes off again when the runner notices the misplay, the Official Scorer should credit the run as scored on a fielder’s choice.

Now I don't think either fielder thrown to a wrong base. If the first throw was good, it would be a third out, so the plan was good. And after 1st baseman reestablished his footing, he thrown the ball home, which was the only play left. The runner from 2nd did momentarily slow down at 3rd though, so I guess this could qualify as "fielder holds the ball" (which does sound pretty vague - holds for how long?). Is that it or am I missing something?

Answer 1

It's difficult to address why a scorer reached a particular decision after the fact. There might be some information we're missing, or they might be interpreting specifics differently.

But coming up with a scenario for this doesn't seem too hard.

Lets assume the ball is slowly hit deep to third, such that the fielder really has no solid play at any base, even to first. With errorless play we would assume all runners advance, awarding the batter a hit and an RBI. If the defense allows other runners to score, we would not award additional RBI.

If the catch were completed too late to get the runner at first, you could also deem it a mental (not physical) mistake to make that throw at all. That would then be a non-error miscue by the defense. No RBI for the second run.

I suspect that an MLB scorer would be likely to award an error in that situation if the poor throw led to the run. But I have heard of leagues where errors are only given for truly egregious situations. (That tends to keep the fielders and batters happier and only disappoints the pitchers).