As the title describes, we'll get right to it. There's some discussion regarding what's the right and wrong way to pronounce particular baseball acronyms, so let's put it to rest.
First, there are three different types of pronunciation styles.
1. Worders. These are typically abbreviations instead of acronyms. For this, you are required to say the entire word for which it stands. AVG and SLG fall into this category.
2. Sounders. These are acronyms which spell an easy-to-pronounce word. For this, best practice is to sound it out and hope you got it right. WAR and FIP are perfect examples. wOBA is up for debate, since its non-weighted little brother belongs to the next category.
3. Spellers. These are acronyms for which one would sound stupid sounding it out but take too long to word it out. Just say the letters you see and you'll get along just fine. ERA, OBP, OBA and other similar ones belong here.
After the jump, find a list of common baseball and saber stats and exactly how you should pronounce them.
AVG - Worder. "Average." If using BA, that's a speller.
OBP - Speller. "oh-bee-pee." Sometimes a worder when shortened conversationally to "on base."
SLG - Worder. "Slugging." Don't try anything else with this one.
OPS - Speller. "oh-pee-ess." Don't be the goofball talking about "psy-OPS" or "black-OPS."
ISO - Sounder. "eye-soh," as it's short for "Isolated Slugging." If you're spelling it out (eye-ess-oh), what do those letters stand for? (nothing!)
wOBA - Sounder. "whoa-bah." It's simply too long to spell out. Or if you insist, wake me up when you're done wording it out.
BABIP - Speller. You gotta spell this one out, fellas. Sorry. "Bee-ay-bee-eye-pee." Sound it out at your own risk.
*% - This is a trick one, where * = anything like "BB," "K" or "SB." You typically will be required to say the entire word of the *, while saying "rate" intead of "percent," while the latter is still socially acceptable.
wRC and variants - Worder. If you're using this you're probably doing a little heavy lifting anyway, so just word this one out. "Runs Created based wOBA."
FIP - Sounder. "fip." Rhymes with "rip."
ERA - Speller. "eee-arrr-aay." If you see a +, just say "plus."
WAR - Sounder. "war." Rhymes with "bore" or "core," not "car" or "bar."
UZR - Speller. Nobody wants to hear you say "uhhh-zerr" so just spell it out. "You-Zee-Arr."
RAR - Sounder. Probably as goofy as "whoa-bah," "raaawr" is still better than stumbling through "R-A-R."
Btw (that's a worder, btw), I'm from Kansas City where we have little other claim to fame than being the general guide for national broadcaster's dialectical and inflection style. This is my only qualification for putting this together. Feel free to debate what should and should not be sounded out, but be prepared to be wrong. Enjoy!
H/t to @splashinpumpkin, @toirtap, @harrypav, and @capitalavenue for their opinions.