Let's look at the numbers:
C. Vivian Stringer: 12 years, 9 NCAA Tournaments, 4 Sweet 16s, 3 Elite 8s, 1 Final 4
Angie Lee: 5 years, 3 NCAA Tournaments, 1 Sweet 16
Lisa Bluder: 19 years, 14 NCAA Tournaments, 2 Sweet 16s, 1 Elite 8
Bluder's numbers aren't better than Iowa's previous two coaches. She's made the NCAA Tournament at a similar rate, and has had less tournament success than Stringer. Bluder's a very good coach, but she hasn't taken Iowa women's basketball to places it's rarely been. There was a 17 year history of success at reaching tournaments and going on deep tournament runs before she got here.
As far as defining average, I'd call Iowa an upper half Big Ten (and Power 5) school in women's basketball. Iowa has a history of success. It has great fan support when the team is successful. Bluder's salary was upper half of the conference a few years ago (source below) and has gone up significantly since.
An upper half Big Ten school should expect to go to the NCAA Tournament most years. Missing the tournament would be below average. Having tournament success would be above average. Elite 8 runs or bottom of the conference finishes are outliers.
https://www.btpowerhouse.com/2015/1...-who-are-the-best-paid-coaches-in-the-big-ten