He did inherit a lot of talent from Raveling but many coaches have screwed up good talent and he produced those first three years at a pretty strong level- the 1987 Big 10 was loaded with IU (national champs), Purdue, etc. as was the 1989 Big 10- Michigan (national champs) and Illinois (Final Four). He also had the coaching acumen to move Gamble, who averaged about 2.5ppg his junior year for George at the 4, to 2 where he used a big senior year to launch a solid NBA career as well as moving a low production guy in Lohaus to the 4 who also then went on to a long NBA career. The 1993 team likely was an Elite 8 or Final Four team until the unfortunate Street tragedy. And he went to the Sweet 16 in his lame duck year with a roster that was entirely his own. And that's without getting into on-court and AAU/HS game behavior of Fran and family- TD had more class in his right hand than Fran does in his entire existence- he is a buffoon.
No doubt TD had some 20-10 years as mentioned but his "highs" are greater than Fran's and the sample size is almost the same- TD got ran after 13 years and this upcoming season is year 13 for Francis. What I find humorous is Iowa fans were big into the phrase "next level" when Slick Alford was brought in and, 23 years removed from TD, they still aren't back to the level they were in 1999.