Upon first hearing this news I felt regret as did many others, but then a couple comments on this thread really made clear the silver lining for Banks. Consider two scenarios:
Banks had 100% confidence that she will return to 100% physical health and performance, or:
Banks has doubts that she will be fully rehabbed, or that her recovery was yet tenuous. She's not going to get a redshirt unless she's "broken." Anything in the merely "subpar" category and she has to play through the year, with no doubt less than satisfactory results. However, by transferring she automatically gets to rehab an extra year without even being "broken." Not only that, but she can go the extra year for a Masters and/or be closer to home, perhaps go to a school that fits her academic interests better, perhaps a school where she will shine on the court. By transferring she turns a situation full of doubt into a situation full of hope.
I'm happy for her.