The main problem is Judicial positions being handed out by the leader of a political party and not being chosen purely on their legal experience and insight.
Like most things in US politics it has completely collapsed due to partisanship and the increasingly dominant power of the Executive branch. In the past the Senate quite often shot down presidential nominees if they felt that they were not suitably qualified for the role. It even happened during Bush II's time when he tried to nominate some crony of his who wasn't even a judge.
Nowadays you get the feeling that if Trump really did nominate someone unqualified like current Senators Tom Cotton or Ted Cruz that they'd end up being confirmed.