The Big Ten has not performed better than the following 3 for sure:
ACC- Multiple recent national championships, more sweet 16 and beyond appearances
Big 12- Multiple recent national championships, more sweet 16 and beyond appearances
Big East - Multiple recent national championships, more sweet 16 and beyond appearances
Looking at the SEC - Kentucky has a championship and a handful of final fours in the mid 2010's.
I would say it is between the Pac 12 and Big 10 for worst conference in the postseason in the last 10-15 years.
ironically, looking at seeding/expected wins, the Big 12, Big Ten and SEC are the worst leagues since the 2019 tournament, and the PAC 12 is the best.
This only looks at games in the first four rounds, as the final four is past where a 1 seed should make it.
This is also incomplete since it doesn't include the sweet sixteen/elite 8 games from this year.
The ACC should have won 32 games and have won 33 (+1) and have 1 team left
The Big 12 should have won 45 and have won 34 (-11), but they have 2 teams left this year and multiple titles in the last 5 yeas
The Big East should have won 20 and have won 19 (-1) with 3 teams left this year
The Big Ten should have won 45 and have won 35 (-10) with 1 team left this year
The PAC 12 should have won 16 and have won 22 (+6) with 1 team left this year
The SEC should have won 41 and have won 33 (-8) with 3 teams left this year
Oddly enough, teams that have titles in the last four tournaments are under performing.
Baylor has won 3 games less than their seeding,
Kansas has won 5 games less than their seeding
Virginia has won 4 games less than their seeding,