1st Play by Infielder
 

NCAA Rules. With R1 stealing, batter hits a blooper into shallow Right Field that F4 fields on a hop and throws to 1st, but before he releases the ball, R1 has touched and rounded 2nd. F4's throw to first is wild and goes into DBT.

In NCAA, would F4 in this situation be regarded as an infielder, thus 1st play by infielder, thus award of bases would be TOP? (BR to 2nd; R1 to 3rd)

Or would F4 in this instance not be regarded as an infielder, thus award of bases would be TOT? (BR to 2nd; R1 to home)

Is there any authoritative written interpretation on this besides our opinions?

F4 is an infielder. The rule says first play by an infielder, not first play in the infield. Infielder is defined as "fielders (usually four) who occupy positions between the pitcher's mound and the three outfielders (usually between or somewhat behind) the bases." No interpretation is necessary.

Depends on where BR is at the time of the throw. If he hasn't touched 1B, then it's two bases TOP; if he has (which would be amazing in the given situation), it's TOT.

It's in the rulebook. I think it's fairly authoritative:

A.R. 1—If the thrown ball is the first play by an infielder, the position of the runners at the time of the pitch shall determine the awarding of bases. Exception—If all runners, including the batter-runner, advance one base before the time of the throw (meaning the release of the ball), the bases awarded shall be measured from the time of the throw, not the time of the pitch. If the throw is made by an outfielder, award bases to all runners from the time of the throw.

I would pose the question in another direction:

Why would an arbitrary line on the field (and the infield/outfield "line" is certainly different from field to field) mean anything? Means nothing for an infield fly, right?

The citations you've received, though, seem to cover your question quite well.

As already stated, an infielder is an infielder however and most importantly though, you must consider the position of ALL the runners, which INCLUDES the batter runner, as quoted above.

From the bold red comment in the OP, I think it would be safe to assume BR has NOT reached 1B (no need to make the throw if BR was there already).

This is a TOP award.

Thanks for your comments men...

This could be one of those situations where the "Shift" is on and F4 is several feet into the outfield. A texas leaguer is hit into shallow right field behind him but he is able to get it on a hop and attempt the throw to 1st. So, for all intents and purposes in this situation, F4 shall always be regarded as an infielder no matter if he is fielding the ball several feet into the outfield...

In the "reverse" situation where the team brings in one of the outfielders to cut off a run at the plate, you could have 5 infielders to whom the rule applies.

So if F4 is playing "right-center-field" position, is he still an infielder?