Garibay will probably score the most points, so his impact will likely be the easiest to measure. Offensive linemen usually have a good year when their impact is least noticed, so Smith's name might be called on a few key blocks, but generally if it's called, that won't be a good thing. Tolbert should be expected to put up OK numbers, but not No. 2 or No. 1 receiver numbers yet. If Williams can get a bunch of sacks, he'd take the honor, but it's unusual for a rookie to have a double-digit-sack season.
So I think Garibay has the best chance as a rookie. Zuerlein scored 129 points last year. Garibay could end up with more than that if he's any good.