i asked that last season! hahahah
i threw this question to a long time heejin fan. so i'll just relay that info. Heejin definitely was instrumental in winning those championships, along with Jeongah.
She was great as a MB (at least a few seasons back), as theloneracer had mentioned, she even won MVP before. But, remember these players have committments in NT too? And who plays OPP in the NT? None other than Heejin. Apparently, she's played the most number of matches as a member of NT.
So, during off league season, she goes into NT. Not much rest i guess, and injuries will start piling up. I think Heejin played her butts off when she was younger. That accumulation could have resulted in injuries, and with injuries, it's really hard to get back into form, when you get no rest. (how long did she rest before being called up for OG?)
For me personally, she isn't prolific as a MB. she seems to have slowed down or lost that MB "senses", if she was great in that past. I dont think she made any blocks today...
Like suminj i love heejin as a OPP in NT with Lavarini, so i would want to see her one day play OPP in league too. if she'll do as well when she's in NT lol