John Elway is not the type of general manager who will accept a quarterback with a midtier ceiling. That's why he parted ways with Tim Tebow four years ago, as it was clear Tebow would be hard-pressed to develop into a top-15 quarterback.
Elway instead decided to take a risk on a 36-year-old quarterback coming off four surgeries, but one who would have a high ceiling if things worked out. After two Super Bowl appearances and one Lombardi Trophy in four years with Peyton Manning as the primary starter, it's clear that risk paid off.
Given Brock Osweiler's performance last year, during which he ranked 24th in Total QBR (48.8) and 28th in yards per dropback (6.0), it's no surprise Elway seemed to put him into the midtier ceiling category and thus was willing to let him depart via free agency.
If Elway's history is any indication, he will look for a high-ceiling option when picking his next quarterback, even if that player comes with some risk. In that case, the best candidate is Robert Griffin III.