He has never had any affiliation with anything remotely resembling a power college football program in his professional career, or really his entire life. The closest thing would be the fact that he spent part his freshman year of college at University of Pittsburgh, which I think most of would agree is questionable at best to classify as a power program either historically or recently. (Forgive me for slightly violating my pledge not to editorialize on this first bullet point... it won't happen again in this thread-starting post, I promise!)
He's now been a head football coach for 9 seasons, including the currently-in-progress but mostly completed 2020 season.
In 8 out of 9 of those seasons, he's finished with a winning record both overall and in conference. The lone exception is his first season at Iowa State, in which he went 3-9 (2-7).
Iowa State went 8-28 (4-23) in the three seasons directly prior to his arrival in Ames, Iowa.
Between 1869 and 2019, Iowa State has the fourth-worst all-time winning percentage of all current Power 5 college football programs... ahead of only Northwestern, Wake Forest, and Indiana.
In the football recruiting classes of 2012-2015, Iowa State finished second-to-last in the Big 12 recruiting rankings once, and dead last in the other three cycles, according to Rivals.com. This was all out of 10 teams.
In the 2017-2020 recruiting cycles--that is, tossing out the still-in-progress Class of 2021 and Campbell's transitional Class of 2016--Iowa State finished 6th, 9th, 7th, and 6th 9 (again, out of 10 teams in the conference).
In the current Class of 2021, Iowa State currently sits at 5th in the recruiting rankings.
Iowa State's worst finish in the Big 12 Football standings over the past 4 seasons (including the currently-in-progress one) is a tie for 4th place.
As of this moment, on Saturday, November 28th, 2020: Matt Campbell has the best career winning percentage at Iowa State of any Cyclones Head Football Coach in the last 100 years, just edging out Earl Bruce's 6-year tenure in Ames in the 1970s.
As of this moment, on Saturday, November 28th, 2020: Iowa State sits alone atop the 2020 Big 12 Football standings.
If Iowa State wins their football games on the next two Saturdays, they will win their first conference championship in football since 1912, when they were members of the Missouri Valley Intercollegiate Athletic Association.