I don't think some people realize how difficult it is to average 9.37 yards per carry (Felix's career average), even over a small sample size (he has 51 career carries).
In NFL history, a running back has averaged at least 9.3 yards per carry for a GAME with at least 20 carries only 25 times. Only four times has a back done it with at least 25 carries.
Felix's career YPC is more than 3 yards better than any other running back who has had at least 30 carries in his career. And it's more than 2 yards better than what any other running back has averaged in his first two seasons (minimum of 30 carries). Will his average go down? Almost certainly. Then again, after he averaged 8.9 yards per carry last season, who would have thought it would go UP so far this season? He has a higher YPC than any other running back who has carried the ball more than once this season.
And finally, since the start of 2008, Felix leads the league in games with at least three carries and a YPC of at least 6.8. He has six of them despite missing 10 games last season. Heck, he's carried the ball in only eight games total, and he's had a ridiculous YPC in almost all of them.