Is tennis like basketball where the seventh worst team in the tournament that Wake would theoretically be playing is likely to be a mediocre low to mid major conference champion?
It doesn't really work like having 1 play 64, 2 play 63, etc. Not a strict S-curve.
Teams 1-16 are seeded in order. Then teams are grouped into 17-32, 33-48, and 49-64 groups. In assembling the regionals, for the placement of the 17-32 group, the committee tries to hew to an S-curve but the 400-mile NCAA driving limit is taken into account. For example if Team #32 is within 400 miles of #1, it's almost certainly going there. But if it's all the way across the country, it's probably not, and the committee will move on to Team #31 to see if they fit, etc.
Obviously it's inevitable that some teams in the 17-32 group end up having to fly, but they try to minimize it. I remember one year we were like #20 and got screwed by being sent to #1 Virginia because we were the only team within driving range (they've now changed it where teams from the same conference can't be at the same site, which makes for a lot more geographic diversity, and plane trips).
For the 33-48 and 49-64 groups, they may keep the S-curve in mind, but I think geography is emphasized a lot more. The at-large cutoff is usually around 43 or so, which means that everyone in the 49-64 group is a conference champ not otherwise ranked in the top 50 nationally. So the short answer to your question is that we won't necessarily be playing the seventh-worst team, but rather will likely be playing a mid-major champion from somewhere around us (think SoCon, Big South, Sunbelt, etc. champ).
Frankly it doesn't matter - there's no way we lose to a team outside the top 50; the more important question is which team from the 17-32 group gets sent to us. This is another reason why it would have been nice to finish ahead of UNC because we're probably pulling from the same pool of driving distance teams and they are going to get the weaker one. Looking at the driving distance teams right now, Kentucky is the only obvious one I see in the 17-32 group and don't know if they would send them to us with them being ranked #20, but I wouldn't bet against it