I solved this last night just before falling asleep, and this morning I opened it up and thought, "What's that square outline in the middle of the grid?" Then when I clicked on the revealer, and all the theme clues lit up, well, ... IMLOVINIT. Three balls outside the zone, and two strikes right down the pipe. I love how the balls are all on the outer edge, too. They wouldn't have to be, of course, but somehow it just makes it that much cleaner. And lastly, about the theme, I briefly bristled at the square-ness of the strike zone (instead of being a tall rectangle), but then I realized that the strike zone changes depending on the size of the batter, and if a 15x15 puzzle grid were up there at the plate, it might well have a square strike zone. HAH!
Honestly, today I like the theme so much that I don't really even care how good the fill is, but let's look around a little anyway. 1A: German export (AUDI) is meh. C-. Maybe even D, just because it's always AUDI drivers who zoom up behind you and flash their lights asking you to get out of their way. 1D: Pop group that broke through at the 1974 Eurovision contest (ABBA), on the other hand, were I to rate it, would get an A. Eurovision gets mentioned in the NYTX!
BODACIOUS (38D: Attractive, informally) is a great word, but I don't really think of it as meaning attractive. Maybe more like "awesome." ANIMUS (57A: Enmity), too, I think of in the more general Latin way of "mind," or "soul." But still, they're good words. I love a SKOR bar, and I love AMES. :)