I think Dale Murphy should be in. The only knock against him is that he didn't sustain his peak production for long enough.
There are many players in the HOF who are far inferior to Murphy. For about 5 or 6 years, he was one of the very best, if not THE best, in the major leagues. There are quite a few players who made it to the HOF without ever being "the cream of the cream" during their era. Harold Baines, for example, made it in recently, and his peak level was nowhere close to Murphy's. Baines was just able to maintain a decent level for a long time.
Murphy is somewhat handicapped by having played for mostly terrible Braves teams at his peak, and for having played in a pitcher-friendly era. His stats don't look all that remarkable compared to top players of today, but things are different now.
Murphy was (and is) also a tremendous human being. Not that that should be a big factor in HOF voting, I guess, but I have a suspicion that part of the reason Murphy faded relatively early is because he was the kind of guy who would never take any illegal substances. I don't know what all was even available at the time, given that he retired in 1993, a little before the MLB steroid era was in full swing. But PED's have almost undoubtedly extended careers of some top players, allowing them to pad their stats and distort what is considered HOF-worthy.