If F3 was not in the vicinity of first base, then
Seo balked when he didn't throw TO FIRST BASE. The rules say you have to throw to a base, not a player. Once he stepped toward first, he had to throw toward first. I believe it was Kenny Rogers last year, who turned to throw to first, and as he was throwing, noticed Teixeira playing WAY back. Rogers ended up lobbing it directly toward first base - slow enough that Tex kept it from rolling away. No balk, and the announcers (one of which is a decent rules guy for an announcer) went on and on about what a veteran move that was.