Felix is at Dortmund. Decent at best. Shows flashes of brilliance here and there. Frimpong is a goal scoring and assists wingback. The right set up will allow him flourish but I don’t think I’d put my neck out and say he’d be great in a traditional back 4. He could be of course but I’d err on the side of caution.
Nonetheless, I see what you’re saying about Mukasa. However, it’ll take a different set of personnel to take that risk of throwing him in the deep end re the first team. I’d even go as far as saying that if Yamin Lamal was at City, I don’t think we’d see him properly till he was about 20.