I agree with tico. Heyward has gotten some hits, he's driven a couple of balls fairly hard this year, and there doesn't seem anything fluky about his respectable, anti-awful hitting thus far. If he can hold at/above .260/.350/.400/.750, that's not too bad for a #7/8 hitter.
I'm optimistic that he can sustain this level; and actually somewhat optimistic that he can further improve on it some.
Lot of guys have been getting hits opposite-way; Heyward got at least one this weekend, and that still seems an untapped opportunity for him. A lot of pitchers pitch him outside half, particularly early in the count; with his height/length, I don't see why he couldn't be able to cover the outside half, if he figured out how. And if he was better able to hit some ground-balls left side against the shift, with his decent speed I'd think some of those could become hits. Slapping a weakish grounder towards third might not constitute hard contact, but there are some singles to be had there. Also think that in past, some of his best contact he'd pull foul. If he's recalibrated a bit so that his best contact is pull-side-fair for hard-contact, and some of his previous-2B-groundouts become opposite-side singles, it could help.