The biggest issue in interviewing is the bad inexperienced interviewers. It's very very hard to be a good effective interviewer and in my experience even otherwise very smart programmers are not great at this. Here's few things that would help to find better match and eliminate lot of false negatives:

1. Pre-filtering should be based on candidate's public contributions at places like GitHub, StackOverflow, Wikipedia etc. Pre-conceived notions of someone being C# or academic is just simply bad.

2. Don't ask question that you didn't had to solve doing your job. It's absolutely the hardest part for interviewer to come up with great questions that distill the problem they had solved on the job in to something that can be described in 10 mins and worked on in about hour. Most interviewers are unable to do this and fall back to puzzles stolen from websites or coworkers like them. If you are not smart enough to form the great question using actual problems in your job than you have no business being an interviewer.

3. Don't do 45 minute interviews. That time is too short. Candidate has already taken a day off, there is no reason why you should limit each interview to 45 mins and make candidate rush. Countless great candidate get eliminated because they fall short of 15 mins, do longer initial chit-chat or just take one wrong turn.

4. Strongly discourage interviewers to look for exactly the right answers. Again hard to do than said. Most candidates that sail through problem have very likely practiced similar problem to death. The bad interviewer than penalize candidates who hadn't practiced that same problem VS who luckily happened to do so. Ultimately you are required to eliminate 80%-99% of candidates and this comparison is so handy that interviewers fall for it despite of knowing it.

5. Good interviewers knows the trickiest part of the problem and are willing to help out candidate without penalties. Bad interviewers considers any hints or help as sign of weakness and are mentally subtracting points. If you are an interviewer who thinks that your job is to give problem, sit back and watch the show then you are wasting everyone's time. Good interviews are lively discussion, two way conversation and in fact a collaboration.

6. Bad interviewers ask seemingly easy problem but that has chance of making a big tricky mistake or omission. Interview turns in to sport spectacle to see if gladiator candidate was able to duck the fire from the dragon that was behind him. Good interviewers make sure problems are real problem and not a competition to set up traps that everyone easily falls in to.

It's kind of bizarre that most companies claim that they have huge headcount to fill and they don't find talent while their "rejects" have already been having great jobs at great companies with nice history of career growth and compensation raises. The real problem is bad inexperienced interviewers who have been molded to ask same puzzles they had been asked and have been trained to have expectation for candidate to magically arrive at correct answer with error free compact code under 30 minutes. It's utter nonsense. The result is that most candidates now keep working on puzzles for months which has little relevance to actual problems in job and not even a remote indicator of candidate's passion or ability to take initiative or collaborate or ship something in real production consistently.