Rotational Player and Threatening Starter's Job
It shouldn't take one playoff game for front offices to realize a very good to elite QB is usually a prerequisite to winning a SB these days.
There are outliers (Flacco, Foles, 2013 version of Wilson, Johnson, Dilfer). But most of those guys either played elite (Foles & Flacco) or were surrounded by stacked positions everywhere else (00 Ravens, 02 Bucs, 13 Seahawks).
The NFL continues to be a passing league. More and more every year. Chances are we won't see an 85 Bears or 00 Ravens type defense carry a QB to a SB again.