So first, lets ignore the fact that a football decision is not necessarily required to be made singularly on stats.
Now, let's get to something more important; stats don't even tell the whole story about stats.
Take my Redskins for instance.
Is Colin Kaepernick better than Colt McCoy? You could probably make a stat based argument on that, and it's indisputable that at some point he absolutely was monumentally better than Colt McCoy.
However...
Colt McCoy now has 3 full seasons under his belt under Jay Gruden, has started and won games as the backup, and has demonstrated a strong understanding of Jay Gruden's playbook. Jay Gruden has expressed immense confidence in Colt McCoy, to the point where people in the area speculated that they would potentially go with McCoy if someone paid the draft pick cost to get Cousins this year. This is despite the fact there were likely other potential quarterbacks out there that, stats wise, could be argued as better than Colt McCoy as well.
Familiarity with a system, trust of the coaching staff to function within that system, and experience with the players on the roster are all clearly FOOTBALL (not business, not even "intangible" personality type things) related things that could lead someone who looks worse in the pure "stats" department to be a more preferred option over someone who is "better" in the stats department.
What's the most obnoxious thing about this whole ordeal is watching non hardcore football fans wading into these discussions making absolutely idiotic arguments or illogical ones within the scope and reality of how the NFL works and has worked for years now.