MOON Myoung-Hwa is a surprise, but if you look at it, Yang Hyo-jin and Kim Su-ji are pretty much fixed, so you only need someone to complement them and bring some skillsets that they don't possess. Yang Hyo-jin is your main blocker, but she's slow. Her knees are also done, making her unable to perform any attack patterns that require mobility. Kim Su-ji is a slide attack specialist whose strength is exactly mobility, but she's not the most prolific blocker.
For the third option, they need a tall blocking presence with faster legs than Yang Hyo-jin (not that Moon is really fast, but she's got the height...). Of course, it would be great if she could score too, but blocking is most important. Park Eun-jin did quite well in that role in 2019. Lee Ju-ah was great in the post-season and would have been my personal choice for the VNL, but she's a Kim Su-ji "type" who plays a similar game (although she brings different abilities). Han Song-yi is a great blocker in V-League and can do what Kim Su-ji does, but she's still unproven as a MB in international games and she's another pair of old legs (although still pretty fast despite her age)... May the best MB win!
Kim Da-in is another interesting one. But honestly, if you HAD to bring three setters, who else could you have picked??? Cho (Slow) Song-hwa? Lee Go-eun? Kim Da-sol? I'm taking Da-in before any of them easily, especially when we're trying to implement a fast style of volleyball. For the Olympics, just bring Yeum Hye-seon and Ahn Hye-jin and call it a day.
Pyo Seung-ju and Kim Ju-hyang will have to fight for that last OH spot. Obviously, with Lee Jae-yeong available, that spot wouldn't have been available, but what can we do... Both have been inconsistent over the last season. For Pyo, it's because she's been asked to do something she never was in her career, be THE leader responsible for both the attack and reception. Like Kim Mi-yeon, Go Ye-rim, Hwang Min-kyeong and Choi Eun-ji, Pyo Seung-ju is a very serviceable number 2 OH. She also has a height advantage and is a better attacker than those names mentioned. It was just too much for her this year as she had to fend off all the serves with a target on her back, while expected to be the second scorer behind Lazareva, and mentoring (carrying) both Kim Ju-hyang and Yuk Seo-young. But as the 12th player who can replace both an OH or an OP at any given time during the game to create a spark, bring me Pyo any day!
In Kim Ju-hyang's case, her inconsistency seems to derive more from a lack of confidence and experience than a lack of skill. It was her first year being a starter and she played stiff and nervously in many games, like someone overwhelmed after realizing the weight she has to carry. She would have greatly benefited from having a real coach who can take her on the side in-game and calm her down. I am eager to see what Lavarini can do with her. She has occasionally shown she could carry that burden and bring her game to another level, like that playoff-clinching match when Lazareva was not 100% and the team needed someone to step up. Even if she doesn't go to the Olympics, this will be a great experience to take the next step in her career.
Like u said, those 2 veteran MB are fixed. As for Pyo, im eager to see her performance once she's given the chance. She play good games when she's focus like during the 2nd PO. Well, they need to play 15 matches and players rotation is crucial. I do hope they can beat big teams this time. Mainly to boost their confidence and regain their rhythm after major changes in lineup