All Mahomes did in his first season as the starter was post the greatest fantasy season in the history of the league. Sure, he’s bound to regress some, but he has room to regress and still be the fantasy QB1 in 2019. Other than Mahomes, there have been 15 seasons since 2000 where a quarterback has averaged 8.5+ yards per attempt on a minimum of 300 attempts. Collectively, those quarterbacks averaged 8.87 YPA. In the following season, they averaged 7.69 YPA, a 13.4% drop. Every single quarterback experienced regression, though some were more drastic than others. Mahomes’ situation (surrounding talent, coaching staff) haven’t changed, so he has a good chance to post another great fantasy season. It just may not be historic.