The plural of “runner-up”

Background

A reader wrote to Wikimedia (OTRS) noting that they found an article with an incorrect plural of runner-up. The corrected one instance, found another, then realized there were quite a few. I offered to do some research, and begin the process of correction, if warranted.

I reviewed a few dictionaries, and grammar sites, and concluded that “runners-up” was preferred to “runner-ups”. I began making some changes, slowly. An editor, active in the tennis area, challenged the changes on the basis that the tennis editors had discussed this in the past, and reached a consensus in favor of “runner-ups”. (I also mistakenly changed the capitalization in a few cases, since corrected.) I did a little more homework, including looking for this consensus. The combination of more homework, and the failure to find this consensus appeared to persuade this editor. See User_talk:Wolbo#Plural_of_runner-up.

I used AWB to made replacements, and began making more changes. Another editor objected, with the argument (in my own words) that there are two ways to form a plural:

1. Multiple people reaching the status of runner-up
2. A single person achieving that status multiple times

This editor suggested that, in the first situation, use “runners-up” while in the second, use “runner-ups”. I stopped editing, asked for a source for that intriguing distinction, and, although no source was forthcoming, decided to halt editing and ask here.

Stats

• “Runners-up” occurs almost 40,000 times in Wikipedia

• “Runner-ups” occurs about 2,000 times in Wikipedia (I have made roughly 200 edits; these numbers reflect those edits.)

These numbers aren't being proposed as proof, but simply provided as evidence of current usage.

Informally, it appears that “runner-ups” is very common in tennis articles, perhaps because many articles about tennis players follow a semi-standardized formats in counts of titles and runner-up status are very common headings.

Dictionaries

• Oxford Dictionary noun plural runners-up
• American Heritage Dictionary n. pl. run·ners-up
• Dictionary.com noun, plural runners-up.
• Merriam-Webster plural run·ners–up play\-nər-ˌzəp, -ˈzəp\ also runner–ups (If I understand my dictionary conventions, this suggests that the second option is acceptable, but less preferred.)

Grammar usage sites

N.B. Many of these will not qualify as reliable sources, but merely offered to show what some common sites say.

• Quora
  • Definitely "Runners-up".
  • Apparently it's runners-up. If you run some Google searches, you'll see that's what everyone uses. Virtually no exceptions, from what I could see.
  • Runners-up. "Runner" is the noun in this phrase, and it is the runners that are multiple, not the up. This reverse noun-adjective structure also exists in Attorney General (Attorneys General).
  • As the answers indicated, it's the noun "runner" which is made plural. 
  • Runners-up. The noun is runner and it is plural, which is runners. The other example like this is passers-by where the noun is passer and making it plural would be passers. With every hyphenated set of words, the noun needs to be identified first to make it plural. The verb is never pluralized.
• usingenglish.com
  • Runners-up is just the plural of runner-up. You can use it when there is more than one runner-up.
• answers.com
  • The correct plural term is runners up.

Multiple people versus multiple event

Note that the Dictionary.com entry includes runners-up, the competitors who do not win a contest but who place ahead of the majority of the contestants and share in prizes or honors,as those who place second, third, and fourth, or in the top ten. which supports the usage in the case of multiple people, but tantalizing is is silent on usage involving multiple events.

However, I have searched in vain for a site, reliable or otherwise which clearly makes the distinction. I have noticed that some places avoid the term and use a different locution .e.g who has more runner-up trophies?

Complications

In addition to the two main options, I have seen other formulations:

• Runners up
• Runners Up (often in headlines)
• Runners–up (en-dash Rare, but occasionally in Wikipedia)

Unless I hear otherwise, I plan to treat each of these as incorrect

Options

1. Accept “Runners-up" as the correct plural in all cases
2. Accept either “Runners-up" or “Runner-ups" but require consistency within a article
3. Accept “Runners-up" or “Runner-ups" depending on whether it is multiple people or multiple events
4. Accept “Runners-up" in the case of multiple people; rewrite to avoid a plural in the case of multiple events (needless to say, far form trivial to implement, but offered in the sense of completeness
5. Other options I haven't considered