I just can't give it to Brock due to how few games he played. Had he played a few more games or the entire season, he would be a lock.
I originally thought Wilson, but after looking at past winners, Wilson would have the worst stats of any WR rookie of the year since at least 1992, maybe before that. Only Percy Harvin and the Carl Pickens had worse WR stats, but they were both fantastic returners on top of their receiving stats. Wilson doesn't have that.
Walker's stats don't blow you away and they aren't as good as many past RB ROYs, but there have been RB ROYs with very similar stats. Todd Gurley, Eddie Lacy, Cadillac Williams, Anthony Thomas all had similar stats to Walker and won the award since 2000.