You guys were arguing with a lot of arbitrary end points and nothing rigorous, so I tried to look up Gonzaga's updated PASE (Performance Against Seed Expectation), but couldn't find it. So I did it myself.
Under Coach Few (2000 - Present)
2.975 total PASE
Essentially, they've won 3 extra tournament games than they were expected to in the 17 years. 0.175 per tourny. Anything positive over a long sample size is good. Few's number is quite good, but not elite. Brad Stevens is at 1.5 PASE per tourny, for example (I can assume he is the GOAT in this stat with a sample size of more than 2 or 3 trips).
Kevin Ollie has a truly ridiculous PASE because of the championship and then missing the tournament entirely when we were bad. He got 5.11 PASE for 2014 by itself, then another 0.45 in '16 by winning the coin flip game. 5.56 total for 2.78 PASE per tourny.