These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Anticlimax Boss: A match between Musashino and Nishiura is foreshadowed early on, but when the two teams finally face each other Tajima hits Haruna's pitch without even trying, and Hanai tops it off with a homerun.
Creator's Pet: Haruna, and the rest of Musashino High School. To the extent that Higuchi has been giving them 50:50 attention with Nishiura since 2008. Just when the fandom thought it was over, the fall tournament began and guess who Nishiura's first opponent is. It gets even worse when you realize Higuchi went into loving detail about the Kasugabe and ARC matches, and then completely glossed over Nishiura's three newcomer's tournament matches so she could throw them into a match against Musashino
Cult Classic: It didn't sell very good in America but it's a very well-known sports series.
For Mihoshi, It's Personal between all of them and Ren, including a Kick the Dog moment from their captain. Kano is weird about it, since Ren was forced off for his benefit and with his approval, because he's serious about being the top pitcher. However, while the rest of the team hate Ren, he apparently still wants to be friends because he knew Ren from before the team. He also believed Ren had actual talent and they had misjudged him — which just makes him even more determined to win their pitcher's duel.note And still be friends.
On the whole, between everyone but these four guys and everyone else, there are no evil rival teams. Even Mihoshi and Tosei are very gracious in defeat.
Die for Our Ship: The backlash among Japanese yaoi fangirls when Shinooka was revealed to have a crush on Abe was incredible. They have taken to writing her name as 死の岡 and 死のーか, using the character for "death." The fact, that the poor girl decided to keep it for herself and not pursue her feelings, didn't stop anyone.
Ear Worm: "Oh boy meetsu GIIIIIRLLL, or a boy meets YUME!"
Het Is Ew: The most common attitude of the part of the fandom invested in shipping, ie. almost exclusively Yaoi Fangirls. Though Shinooka x Mizutani will sometimes be tolerated, as it would keep the former away from Abe.
Ho Yay: Everywhere. The story runs on bromance of the most emotional sort and the only prominent and semi-prominent female characters are their coach (a few years older than the members), their manager (who is a part of a love triangle, but a revealed late and an extremely downplayed one) and the members' mothers.
The tough love relationship between Ren and his catcher, Abe. Yaoi FangirlsSquee at the scene where they hold hands in a bush, and Abe assures Ren that he "likes [Ren], more than just as a pitcher".
Ren: I - I - like you too! Abe: Uh, great, thanks... (thinks:Did it sound that creepy when I said it?)
No mention of Hanai and Tajima? Or Sakaeguchi and Suyama after the latter's heartfelt, hand-holding encouragement during the middle of a game?
To add fuel to the fire, several of the boys have decided that tickling is an appropriate way to relax each other before going up to bat.
The Ho Yay extends to the members of the other teams: Takase of Tosei breaks down in tears after losing to Nishiura because he "wanted to be able to play more together" with the catcher, a third-year who's graduating, and ARC has Ootagawa's inexplicable devotion towards team captain and catcher Yoshida.
An early example: Hatake appeared to be literally in love with Kanou and bullied Mihashi out of desire to be paired up in the game with the former instead of the latter. Kanou himself in turn had strong feelings for Mihashi that sometimes seemed romantic.
The battery in general is treated almost like a marriage in the most teams and some of the halves (like Abe) take it very seriously and become basically life partners with their "significant others".
Just about any two guys in the series will be shipped together by the fandom. In some cases it's justified fairly well, including some cross-team romances such as Abe x Haruna and Rio x Tajima.
Moe: Mihashi is an example of the rarer male version.