The three wins in the NCAA Tournament isn't the demonstration of Holloway as a good coach.
Saint Peter's is a HARD job. The fact that he built a team over the past four years that competed at the upper end of the MAAC and was in a position to get to, and win, NCAA games is the real accomplishment. That team wasn't built on the back of some superstar player, but rather hard work, strong defense, and good guard play. That stuff doesn't happen without Holloway as the coach.
The wins in the NCAA were icing on the cake, but those games weren't total flukes. They controlled the tempo of the game against Kentucky, Murray State, and Purdue as a result of coaching decisions.
I don't know what the ceiling is for Holloway at Seton Hall, but am pretty sure he will have hard nose, scrappy, tough teams. He did a lot, with very little, at Saint Peters.