I watched Aaron play for the past 18 months (since he signed), and I liked his 1v1 ability, his tackling, interceptions, blocking crosses and recovery pace, not the best in the air, but not that bad really, and usually fullbacks aren't very strong in the air
My issues is his on the ball ability which i can't understand, some moments he will dribble past opponents or give a nice pass to a forward player on his own half, or exchange a nice one-two, and sometimes his touch is loose and he misplaces the pass!!.. perhaps he will improve there with time.
however, he hasn't played with a "Natural Right Winger/Forward" in Ole's preferred 4231 formation, Greenwood cuts to his left and attacks the space to shoot, Mata tucks into the center to exchange passes with Bruno or Martial or Rashford, he didn't play with a winger who uses his overlapping runs (Shaw and Telles are sometimes found by Rashford or Bruno when overlap), and as everyone can see, United play mostly from the left and overload that area, and once Shaw or Telles go up, Maguire goes to the left back area to cover, Lindelof comes to the center and Wan Bissaka drops back (which seems how Ole prefers his team to shape his defense when in possession and attacking from wide, Shaw also drops back if Wan Bissaka is high up)...
I still have high hope for him and as the topic suggests, perhaps we will need someone to cover him if Williams is moved on, I like Trippier and he is a quality player but i doubt he would be happy to play second fiddle to Wan Bissaka.
Perhaps someone like Max Aarons who could be tempted to join a big club, is young and willing to compete for a starting place against Wan Bissaka.
I also like Jonny from Wolves if he was fit, he is quite versatile and might be willing to be a backup to Wan Bissaka