I don't believe the general use of this expression comes from the golf use - which would explain the discrepancy - though the two are closely related.
The word par has many definitions, including average or normal amount and usual/accepted standard.
Therefore something below par is below average, or below the acceptable standard - hence the usual, negative, meaning of the phrase.
In golf a hole's par is the number of strokes considered average or standard to complete it, and being under par means using fewer strokes than average - which happens to be a good thing, because of how the game works.
I was intrigued by the "adjective ladder" data in a writeup by Hicks et al. cited by a linked answer to a related question in the comments, but I wanted to see it as a graph with error bars to help me gauge similarity and variance. I've plotted it below.
I recommend choosing just a handful of these key terms from this chart whose error bars are well separated from each other with somewhat similar distance between them. Perhaps:
- Awful (1.9 ± 0.08)
- Limited (3.8 ± 0.09, abysmal + 1.9)
- Fair (5.4 ± 0.08, limited + 1.6)
- Good (6.9 ± 0.10, fair + 1.5)
- Incredible (9.0 ± 0.8, good + 2.1)
The study has its own similar list of eleven items (abysmal, awful, bad, poor, mediocre, fair, good, great, excellent, amazing, phenomenal). Choosing a subset of six of those would simply entail taking every other: abysmal, bad, mediocre, good, excellent, phenomenal). For five, remove either abysmal or phenomenal.
Be careful not to pick terms that are too obscure! "Abysmal" and "Middling" just aren't popular words. (Though note that popularity is not the same as familiarity.) Consider checking Google Ngrams. Here are the most obscure words out of the 24 on the list (since WWII):
Fewest occurrences in printed books (via Google Ngrams):
Further research needed!
This paper had good methodology, randomizing the list, asking subjects to sort it, then rate it, and a few other tasks the helped them determine subjects' familiarity with each term. They found that "middling" was left blank by most participants, presumably due to a lack of familiarity.
When choosing words, try to avoid the less popular ones (like "middling"). I'd like to see "dismal," "average," and "heroic" in there as well, but keep the list from growing too large.
A larger version of this study could be broken down by region and educational level. If using something like Amazon Mechanical Turk, I suggest restricting participants to regions where English is the primary language rather than the lingua franca.
Best Answer
From Wikipedia:
Regardless of the origin, the term "low man on the totem pole" is generally understood to mean LEAST important. Using it to mean most important would probably just lead to confusion.