1st year analyst in 2 year rotational program. Move to different department, or stay put?

I had some autonomy in choosing my next (1-year) rotation. The manager ranked me, I ranked them, and we were paired. I am supposed to rotate in 1 month.

Although it is within my department, it’s completely out of my skill set and is a highly quant modeling role (using MATLAB). I thought it would be good experience that I wouldn’t be able to get had I been an applicant from outside the organization since I’m not qualified, plus, the manager seemed to believe I was capable and that he would support my learning. However, he has since resigned and his analyst (been with the org 5+ years) will likely be my manager. B/c I hadn’t originally interviewed with the new manager, I don’t feel they understand how under-qualified I actually am, and they will likely expect more from me than the now-resigned manager. Although I can work hard and learn as fast as possible, I still feel that I’ll hit a wall pretty fast. I don’t know what I was thinking when I chose this rotation rather than one I’m qualified for, and am now hesitant to start it in a month. Anyways, I know I would do much better in a different role in a different department. It is actually in a completely different city where I know I would thrive, too.

So, should I apply for the role I know I would be good at in the different department, or do I stick it out for a year then move into the different role? I am scared to bite the hand that feeds me, but also terrified to fail.