I'm with ChiCat on this one. Making the postseason is an important benchmark (maybe the only benchmark) for coaches at decent schools.
At literally any other job where you are in a similar managerial/GM/CEO position, it is unforgivable to fail to hit minimum performance expectations three years in a row.
To 33's point, you can also look to the actual coaching and team trajectory throughout the year to judge a coach, which is why I think most of us agree oscar should be gone regardless. But failing to make the Tournament once again should be automatic.