I realize this is very subjective... not only is it a matter of opinion, but the term 'offensive coordinator' has not always been used. For many years our "backfield coach" was the primary guy responsible for developing our offensive game plan and calling most of the plays.
By my count, Ricky Rahne will be Penn State's 11th "offensive coordinator" since 1950. My ranking of the previous ten:
10. John Donovan (2014-2015)
9. Al Michaels (1950-1953) One of the three best defensive coaches in school history, was also a very good scout/coach on offense.
8. Bob Phillips (1973-1980) Was the first coach JoePa ever hired. Only guy to coach EVERY offensive position at one time or another at Penn State. Led many productive offenses including '73 and '77.
7. Fran Ganter (1984-2003) Developed many solid/great offenses for over 20 seasons including best-ever '94 one.
6. Galen Hall (2004-2011) Was a hugely successful OC at Oklahoma for many years; former PSU QB who led some truly high-octane offenses in the late 2000s; also a head coach at both the college and professional level.
5. Dick Anderson (1981-1983) One of the best coaches in school history, mostly of offensive linemen and TE's; was only OC for three seasons before taking a HC job at Rutgers but achieved consistently high offensive production despite brutally tough schedules.
4. Joe Paterno (1954-1965) Brilliant developer of QB's (sent seven into the NFL); helped transition PSU into modern-era single wing football where the QB is more than just a glorified blocker. Overcame shortages of scholarships to help put PSU football back on the map.
3. Bill O'Brien (2012-2013) Was also head coach during this time; despite severe shortages in talent/scholarships, oversaw very high offensive production in both yards and points.
2. Joe Moorhead (2016-2017) Only on staff for two seasons, but crafted juggernaut offenses in both.
1. George Welsh (1966-1972) Promoted after JoePa became HC in '66; led a tremendous resurgence of PSU offensive production over the next seven seasons. Developed great backs including Charlie Pittman, Bob Campbell, Lydell Mitchell, Franco Harris & John Cappelletti in just a few short years. Went on to be highly successful HC at Navy & UVA.