It is being reported that she is transferring as graduate transfer. If so she would be eligible to transfer within the conference and be eligible immediately. Just like Austin Kendall QB backup did recently and is now contending for the starting job at West Virginia.
However, WVU did have to get OU's waiver for Kendall's immediate eligibility due to conference intraconference transfer rules.
Erin could easily prefer playing 10 minutes per game in Waco to playing 18-20 in Lubbock. Much easier to feel great about your accomplishments when you are contributing to victories instead of defeats. That is why they call WBB a team sport.