I am relatively new to this case. I listened to Serial this summer and have gotten through three episodes of Undisclosed, but I've read some articles about the other episodes.
To add on to the comments about Baltimore police not properly investigating this...one thing I have never heard addressed anywhere is what they were doing with Hae's case in the weeks between her disappearance and her body being found. In my community, we have had two college students go missing in the past 5 years. In both cases, there were many news releases, news conferences, searches, etc., in the hours, days, weeks following their disappearance. Everyone in our community, and half the country, knew these young adult women were missing and some variation of the details of the last time their friends had seen them.
With Hae, we know the police called some of her friends the night she disappeared. Hae's friends didn't get worried about her until a few days later. That suggests there were no follow-up interviews with her friends later that first week and no news coverage. Surely the police contacted, or tried to contact, her dad to determine Hae wasn't with him? I know missing adults are treated differently from missing minors, but come on, Hae was a good student in the final semester of her senior year, in love with a new guy. The likelihood she would just choose to leave seems slim to me, and a couple of phone calls should have told police she wasn't with her dad.
The reason I harp on this is because in other investigations, Hae's friends would have been interviewed again in the days after she went missing. Their memories would have been fresh, no uncertainty about what day really was the wrestling match or did they see Hae after school. And probably, those memories would have stuck with them, along with the memory of being interviewed, and they would have shared that with Koenig.
Another thought: I am not convinced there was no wrestling match the day Hae was murdered. Papers do sometimes get details wrong; they may have printed the wrong dates or the wrong schools. It seems like if Hae had stood up her friend who was the co-manager the week before, she would have then spoken to the co-manager in the days following and said something like, "Hey, I'm really sorry about the other day." The fact that the co-manager doesn't remember that, or any convo with Hae after that match, makes me believe it could have happened the day Hae died.