Virginia Tech isn't a great example to use when comparing conference record to the rankings. They are a different team with Hunter Cattoor in the lineup (just look at him tonight against Duke so far), and most of those conference losses came with him out of the lineup. If he's healthy, they wouldn't be anywhere near the bottom of the league (and against one of the more difficult starts to the schedule among ACC teams, they've only seen BC among the bottom feeders). They would more likely be in the 4-4, 5-3 range in conference play given all the close losses they had without him. But at the same time, they'd be ranked higher than 47 in his system.
But to play devil's advocate, if a 1-7 team in conference play being rated in the top 50 is a sign of the ACC's strength, then what does it say about the ACC that Florida St. is 5-4 in conference play yet are rated outside the top 140? It's a tough sell for me that a team that has two non-conference wins and losses to Stetson, Troy, Siena, and Stanford is a good team. They have had the benefit of getting to play against more of the bottom of the league than a Virginia Tech has, but they also have a road win at Pitt.
FWIW, I don't think this is the worst the ACC has been. Kenpom's numbers may say it is, but Louisville is an absolute anchor and BC/Notre Dame/Georgia Tech/FSU aren't helping matters. How he tries to rank conferences is he tries to determine what the quality of a team would be that would be expected to go .500 in conference play. Even if the middle of the league has quality, those five schools will torpedo that particular metric. 2012-2013 are worse to me because they lacked depth in the middle of the league, but neither has the equivalent of a 2023 Louisville in that league so he would rate the ACC in those particular years as 'better' than it is ranked in 2023. But this year's ACC also isn't on the level of this year's Big 12, and it isn't as strong as the ACC was during 2015-2019.