This is a well-constructed theory, without exaggeration and mentioning the possibilities.There's 2 possible outcomes:
1. He trained seriously and he come back stronger (i won't say top 3 but stronger than top9 for sure especially now with his unc situation)
2. He fumbled hard and did 0 training, only drinking and doing the deed all day (highly doubt it but still a possibility).
I agree, it's unlikely that he wasted his time, ranking in the new top 9 is reasonable, after all he's someone the MC must beat, he can't be a weakling.