You'd have to bring O'Donnell back in, even though he's been disappointing.
I get the square pegs/round holes argument folk are making, but with what's available, it must be tempting to go with the best you have (?) and find a way to make it work. Maybe.
Johnstone at least looked interested, but moving him into an unfamiliar position on his second start at 17 would obviously be really unfair on the laddie.