Showing that a small sample is disproportionately affected by a single run is not cherry picking.
Right, and comparing full year stats to 5 games isn't fair, either. Through 5 games last year, Blount was averaging 3.67 yards per carry, just a tenth of a yard more than Gillislee is this year, and that included the 41 yard touchdown run against the Texans. Take that away and Blount was averaging just 3.31 yards per carry through the first 5 games.
And imagining that Blount was more consistent than Gillislee is wrong, too. Taking out runs that resulted in a touchdown from inside the opponent's 3 yard line, Blount gained 3 or more yards on just 52% of rushes last season, and 4 or more on just 41% of his rushes (taking out TDs from 3 or fewer yards out). Taking out Gillislee's short touchdowns against the Chiefs and Saints, he's gained 3 or more yards on 62% of his rushes this year, and 4 or more on 51%. I don't have time to calculate short yardage success rates but I'm not sure there's a discernible difference thus far.
Based on those success rates, over a full year, Gillislee would rate among some of the better running back seasons of the last decade (for example, Ray Rice in 2009 and Shaun Alexander in 2005 are comparables in this measure of success, though both broke off long runs with more consistency than Gillislee) while Blount's 2016 was Antowain Smith-esque in this category but more impressive in his rate of 10+ yard runs. In other words, Blount gained his yardage in chunks on big runs while being stuffed quite often, while Gillislee has been chugging away with consistent carries of 3-6 yards but failing to break big ones. Pick your poison, though I think Gillislee will break a few big ones because he's been real close and over the past three years he's been consistently one of the bigger home-run hitters in football on a per-carry basis. As noted, though, sustaining that over a full season is the trick.