Well, he did pull off the biggest comebacks at the time in both college and the NFL playoffs. The Maryland Terrapins were losing at the half to the Miami Hurricanes, and Reich came back from a 31-0 deficit to win the game. In 1993 he led the Bills to The Comeback in a game that still sounds like it's from a movie and not reality. Houston ended up leading 35-3 in a home field playoff game that would eventually lead to the Bills losing Super Bowl XXVII . Nobody knew it at the time though, because fans were busy streaming out the exits.
That's when Frank Reich proved he was more than just a Clipboard Jesus. In the third quarter, he rose again, and those fools in Houston never knew what hit them. The game started closing. A botched kickoff led to great field position. A few passes then a diving touchdown by Kenny Davis (who in some ways ran like Mathews suddenly is with the big dives and things) and the game was 35-10.
An onside kick and quick strike to Don Beebe, they were making it a respectable 35-17. A bad punt and a few quick no huddle strikes made the game 35-24. Soon after a tipped pass led to an interception that set up a touchdown from Frank Reich to Andre Reed. 35-31. A fumbled field goal attempt, a big run, and a perfect pass set up a 38-35 Bills lead that led to an exchange of field goals ending in Frank Reich's Buffalo Bills on his way to another eventful riding the bench through an AFC Championship and Super Bowl.
Later, Bill Polian took him to Carolina as a QB, and about a decade later to the Colts under Dungy and Caldwell where he worked as both a QB and offensive assistant. He spent last year as a WR's coach under Whis.
Just think about who he learned from who aren't on the Chargers staff. Bill Polian, John Butler, Marv Levy, Tony Dungee, Jim Caldwell, Wade Phillips, Jim Kelly, James Lofton, Andre Reed, Thurman Thomas, and Barry Sanders (they had a brief time together in Detroit in 1997.)
His time in Detroit also meant that his QB coach was Marc Trestman, now running the Bears, and he handed off to Barry Sanders back when 2,000 yards rushing in a season meant something. He also started for the Jets at one point, but since it's the Jets you can probably guess how that went. He never buttfumbled, at the very least.
So Whis and McCoy might get credit for a lot of the decisions being made, remember that at every position there is someone with a crazy history that Telesco, McCoy, or Whis have worked with over the years that could fill this void. In FR14's case it was both Telesco (Indy) and Whis (AZ) who have worked with him.
Apparently Mike McCoy is also now sold that FR14 + PR17 = SB XLVIII.