I was wrong.
It has become a commonplace to pluralize "RBI" as "RBI." Not "RBIs," as Webster's prefers and God intended.
Some people point out that the R in RBI stands for Run (run batted in), and note that the plural of the spelled-out version is "runs batter in" not "run batted ins." And the abbreviation for that would be RBI. This is mistaken for cleverness.
|Yoenis Cespedes had more RBIs than letters by April 26 of the 2016 season.|
1) An initialism, like an acronym, is treated as a word on its own, generally a noun. To follow their logic, you would have to refer to an RBI as "a RBI," since you wouldn't call it "an run batted in." But since RBI is treated as a word, it starts with a vowel sound (ArrBeeEye) and therefore gets an An.
2) These folks have no problem using CDs as the plural for CD (compact disc), and that is correct. And yet I do not hear them complaining about CDs for certificates of deposit, although this is standard nomenclature for banks and beyond. A banker who walked around bragging about the number of CD he had sold would be considered a dumbbell. (See also: POWs, MREs.)
3) "RBIs" had been pluralized this way since 1948. The New York Times used it at least as far back as 1950. I'll grant you that popularity and longevity doesn't equal quality---look at Madonna---but in the case of language, persistence of usage is all there is. That's how "scarf down" became accepted for eating a lot, although it was an erroneous substitution for "scoff down." So even if you don't like RBIs, there's justification for it based on tradition. If you felt vindicated because you used "enormity" to mean "great size" and not "great evil" and you were corrected but then Webster's said it was okay, then you have to concede the importance of usage and convention. (And on that note, I acknowledge that pounds per square inch is always singular, PSI; very few people say "32 PSIs"--but that's an engineering outlier. STEM have their own conventions.)
4) People who would allow the use of the S for something like DVDs, where the last word (disc) is the pluralized one, would have to refer to RBIs as RsBI. Why change the rule of pluralization depending on where the noun is in the initialism? Or they could just make all initialisms plural without an S (1 DVD, 2 DVD); good luck getting that accepted.
That's my blow for the proper use of language for the day. Now, mind your P's and Q's out there, kids.
P.S.: "Ribbies" is fine if you like sounding stupid.