The Big 10 hasn't won a tournament since 2000, Pac hasn't won a tournament since '97.
I disagree with your post.
Winning the tournament isn't what matters. Getting to the sweet 16 and elite 8 are what matters for seeding. P5 conferences crush the Big East on that metric since the split. Villanova has been the Big East's one trick pony, like Gonzaga in the WCC and gets seeded like it.
2019: No BE team makes the second weekend.
2018: Nova NC. Seton Hall made it to the second weekend in 2018, but Xavier couldn't manage it as a #1 seed.
2017: Villanova missed the 2nd weekend as #1 seed in 2017 but Xavier did make a final4 as a #11 and Butler made a sweet 16.
2016: Nova wins a NC, Xavier wins one game as a #2 seed.
2015: Xavier gets to the round of 32. Nova wins one game as a #1 seed.
2014: No Big East team gets to the 2nd weekend.
So yes, two NCs and one final 4 from Xavier. But the depth of teams playing into the second weekend is not good since the split. I do think UConn can help with that. Seeds for everybody not named Villanova reflect that.