The only reason I can think of for not buying Aarons for £20m is that Poch doesn't want him or they think he should be worth closer to what we paid for Clarke.
I don't agree as I think Aarons is a great fit at a position that is weak this window (and English), but that could be the club's thinking.
Think Poch has decided that Foyth might be our RB for the next five years or so. If I’m not mistaken, he’s been playing in that position for Argentina too.