From 30 teams, we're now left with four: the Orioles, Royals, Giants and Cardinals. Those four teams each come from wonderful cities filled with rich culture and passionate fans. But some fans take their passion to another level -- some fans write songs for their favorite teams.

To get ourselves ready for the upcoming Championship Series, we've culled through the depths of YouTube to track down some of the best anthems from each of these fan bases. Let's see what they can tell us about each team's odds of lifting the Commissioner's Trophy in the Fall Classic:

ALCS

Baltimore Orioles - "Oh Oh Orioles" by Warning Track Power

There's a lot to like about "Oh Oh Orioles:" the throwback-vibe, the charming video and the guy singing into a baseball. The song is catchy enough for even a neutral to come away with a fondness for Baltimore, and surely the die-hard O's fans can rally behind the song's "Come on, Orioles!" chorus.

Plus, most importantly, the main guy is singing into a baseball. We really can't point that out enough.

Lyrical highlights:

"Come fly along with the birds to the top of the American League!"

"Come on sing it with me: Oh oh oh, come on, Orioles!"

Kansas City Royals - "Big John Mayberry" by Unknown

Now, we normally have a "no covers" rule when picking out great fan anthems (hence the lack of any Lorde renditions in this spot), but we're gonna make an exception for "Big John Mayberry," because it's amazing that this thing exists.

According to the YouTube uploader, this Mayberry-themed cover of "Big Bad John" by Jimmy Dean was released as a 45 rpm single sometime in the early 1970s. Interestingly, Mayberry's son, John Mayberry Jr. uses the original Dean version as his own walkup song -- although, if he had a copy of this bad boy, he'd probably opt for that instead.

Lyrical highlights:

"Some say they saw the writin' on the locker room wall; Big John had come to town to play a lot of ball. And when they saw his average starting to climb, they knew he'd be around for a long, long time."

NLCS

San Francisco Giants - "Giants Bluegrass Fight Song" by Hot Buttered Rum

Any song that starts by painting the image of the band pluckin' away in a kayak out on McCovey Cove is already great. Everything else is just a nice bonus on top.

This particular fight song also gets a bump due to recency - it was recorded just this month as the Giants claimed a trip to the NLDS. And while bluegrass isn't a genre one would ordinarily associate with the West Coast, it fits San Francisco's brash eccentricity well.

Lyrical highlights:

 "Anything can happen: it's an even-numbered year."

"Duffy and Susac: they saved our pennant race. Buster Posey's lookalike is playing second base."

Honorable mention: Born Giants Fan.

St. Louis Cardinals - "David Freese" by JAMA

Following in the grand tradition of Troop 41's genre-defining "Do the John Wall," JAMA's ode to now-Angels third baseman David Freese is an astoundingly thrilling theme song.

Sure, it's named after someone who's no longer on the Cardinals, but don't let that fact make you think JAMA is any less of a Redbirds fan. While Freese is the inspiration for the name, this song is all about loving the Cards.

Add to that an A+ music video, and you've got my personal favorite song on this list. After all, if you're writing a song about a Cardinal, you could do worse than the guy responsible for this:

Lyrical highlights:

"All my clothes are red and white, so I'm lookin' like I'm Santa."

"David Freese, you have a gift, now open up and see: it's a trophy - three letters: M-V-P."