I am going to give you a quick statistic lesson. There are variables to take into account when doing statistics. Going purely on national stats when regarding stats is a poor indicator of how a coordinator is doing. Historically a place, such as duke, often has a hard time getting in recruits and being successful in football. Taking that into consideration here are some stats that reasonably support roper:
Duke 2008-2013:
-Most Passing Yards/TD by player 2006-2009 Thaddeus Lewis
-Third Most Pass yards/TD by player 2009-2012 Sean Renfree
(That means two of the top three best passers in Duke history were under his offense. Spurriers two highest QBs at 5/8)
-Most Rushing TDs by player in school history beating the second most by nearly 25% Brandon Connette
-6th most rushing yards by a player ( Would have been top five it followed Roper's trend his first two years - fell off once Roper left) Jela Duncan
- 14th /15th most Rushing yards in school history by a player
-Most Receiving yards by a player in school history - Connor Vernon
-Second most Receiving yards by a player in school history - Jamison Crowder (3/4 years most productive year while Roper was there )
-4th most receiving yards by a player in school history
So basically Roper, under his tutelage, produced the most productive offense stats in Duke history.
Duke 2008-2013:
-Most Passing Yards/TD by player 2006-2009 Thaddeus Lewis
-Third Most Pass yards/TD by player 2009-2012 Sean Renfree
(That means two of the top three best passers in Duke history were under his offense. Spurriers two highest QBs at 5/8)
-Most Rushing TDs by player in school history beating the second most by nearly 25% Brandon Connette
-6th most rushing yards by a player ( Would have been top five it followed Roper's trend his first two years - fell off once Roper left) Jela Duncan
- 14th /15th most Rushing yards in school history by a player
-Most Receiving yards by a player in school history - Connor Vernon
-Second most Receiving yards by a player in school history - Jamison Crowder (3/4 years most productive year while Roper was there )
-4th most receiving yards by a player in school history
So basically Roper, under his tutelage, produced the most productive offense stats in Duke history.