Intersting chart here provided by ASU that shows that backup quarterbacks, for one reason or another, rarely get to start in any given season
1997: Ryan Kealy (11 starts), Steve Campbell (1 start)
1998: Ryan Kealy (9), Steve Campbell (1), Chad Elliot (1)
1999: Ryan Kealy (11), Griffin Goodman (1)
2000: Jeff Krohn (9), Griffin Goodman (2), Ryan Kealy (1)
2001: Andrew Walter (2), Jeff Krohn (9)
2002: Andrew Walter (10), Chad Christensen (4)
2003: Andrew Walter (12)
2004: Andrew Walter (11), Sam Keller (1)
2005: Sam Keller (7), Rudy Carpenter (5)
2006: Rudy Carpenter (13)
2007: Rudy Carpenter (13)
2008: Rudy Carpenter (12)
2009: Danny Sullivan (9), Samson Szakacsy (2), Brock Osweiler (1)
2010: Steven Threet (11), Brock Osweiler (1)
2011: Brock Osweiler (13)
2012: Taylor Kelly (13)
2013: Taylor Kelly (14)
2014: Taylor Kelly (10), Mike Bercovici (3)
2015: Mike Bercovici (13)
2016: Manny Wilkins (10), Brady White (1), Dillon Sterling Cole (1)
2017: Manny Wilkins (13)
1997: Ryan Kealy (11 starts), Steve Campbell (1 start)
1998: Ryan Kealy (9), Steve Campbell (1), Chad Elliot (1)
1999: Ryan Kealy (11), Griffin Goodman (1)
2000: Jeff Krohn (9), Griffin Goodman (2), Ryan Kealy (1)
2001: Andrew Walter (2), Jeff Krohn (9)
2002: Andrew Walter (10), Chad Christensen (4)
2003: Andrew Walter (12)
2004: Andrew Walter (11), Sam Keller (1)
2005: Sam Keller (7), Rudy Carpenter (5)
2006: Rudy Carpenter (13)
2007: Rudy Carpenter (13)
2008: Rudy Carpenter (12)
2009: Danny Sullivan (9), Samson Szakacsy (2), Brock Osweiler (1)
2010: Steven Threet (11), Brock Osweiler (1)
2011: Brock Osweiler (13)
2012: Taylor Kelly (13)
2013: Taylor Kelly (14)
2014: Taylor Kelly (10), Mike Bercovici (3)
2015: Mike Bercovici (13)
2016: Manny Wilkins (10), Brady White (1), Dillon Sterling Cole (1)
2017: Manny Wilkins (13)