I don't think anyone is going to have a chance to make any sort of realistic case for Varsho ever providing much more than a touch above league average offense in a typical season, but that's a far cry from trying to make a case that the guy has never produced at the plate and is never going to produce ever again. Despite the tough 2023 season he still has produced a 96 wRC+ for his career up to this point, and he's shown nothing to categorically prove that he can't return to previous levels of success or improve his 2023 results. This is a player who had really nice minor league numbers, and in his first two seasons as a regular he produced league average or slightly better offensively. His early projections each show a fair bit of improvement from the 2023 struggles, with ZiPS projecting a 109 OPS+ and Steamer projecting a 108 wRC+. Perhaps those might be a touch optimistic but if two separate projection systems expect a significant bounceback from a single down season then it seems perfectly reasonable to expect for this to occur.
XWOBA is not a perfect stat, and on it's own does not paint a complete picture of player performance in a singular season. It has a rather glaring omission in that it does not include spray angle, so as a result it can tend to undervalue players who have the ability to pull fly balls into the seats despite underwhelming exit velocity numbers. WOBA and xWOBA are not 100% correlated to each other, and as such there will be seasons where a player outperforms their expected stats, and seasons where they underperform their expected stats. Varsho had one season where he outperformed his expected stats by 20 points, and 1 season where he underperformed his expected stats by 10 points. With a 100% direct correlation perhaps his career wRC+ output would drop by a few points, but this wouldn't likely be a drastic swing dropping him to something like a career 80 wRC+.
If you look at Varsho's home/away splits there is one particular component which sticks out like a sore thumb.
Home vs R 52 wRC+
Home vs L 84 wRC+
Away vs R 105 wRC+
Away vs L 120 wRC+
Varsho's 2023 numbers were essentially ruined because he struggled against right handed pitching in the Rogers Center. This is a player with a 101 career wRC+ vs right handed pitching, so there is good reason to expect that this will be a crazy anomaly which is not going to happen again in the future.
You are making this grand declaration about the book being out on Varsho after a single down season at the plate. From the listed splits it appears as though he only had a massive hole against right handed pitching, but then only at home at Rogers Center. I guess opposition pitchers chose not to exploit this uncorrectable hole on the road in order to be fair to Varsho or something.
You have declared that Varsho has some sort of fatal flaw in his swing where he has no chance to make adjustments. Varsho actually made an adjustment by adding a toe tap in early August, and this immediately saw an improvement to his results. Over his last 50 games he produced a 116 wRC+ including incremental improvements to his batted ball metrics, strikeout and walk rates, with the biggest gains seen in a return of his HR/FB rate returning to values more resembling his career norms.