Agreed, the top 6 are clear in my mind as well.
If ISU starts 3-1, the game in Lubbock will be pretty huge for bowl implications I think.
I think that is tough to say in a vacuum. Let's say ISU takes a 3-1 record into Lubbock on October 12th. By then we'll also know a fair bit about Kansas, Baylor and WVU and that'll also be big for how important beating Tech is for a 6-6 or better season
By October 12th WVU will have played six games, including Maryland, Oklahoma, Oklahoma State, and Baylor. Taking Baylor out of the equation if they go 0-3 against the other three then I think we can legitimately think we'll beat them to end the season. If they beat Maryland but lose to the Oklahoma schools then a win against Tech becomes much more important to go bowling. If WVU goes 2-1 or 3-0 against those three schools then a win against Tech is essential for a bowl, since that means we probably won't beat them.
By October 12th Baylor will probably still be a question mark. They will have only played a Louisiana-Monroe team that was good last year (but I have no idea if they will be this year) and K-State. If they lose to Louisiana-Monroe that is a great sign for us. But if they win that doesn't tell us much. And if they lose to K-State that doesn't say much, if they beat K-State that is a bad sign for the Baylor game but a good sign for the K-State game. So if we go into Lubbock at 3-1 the Baylor game will still be a question mark.
By October 12th Kansas will either have been exposed as a team we can pencil in as a win or shown to have improved significantly and be a team we have to worry about.
tl;dr It is possible that going into Lubbock at 3-1 will be huge for bowl implications, but it is also possible that there will be at least three games left we'd be favored in (Baylor or K-State, Kansas, WVU).
