Legohamster
Ian Walker
Defensively he is weak, and will be targetted. He'll also have Sissoko and Alderweireld looking out for him, and (hopefully) Moura ahead and tracking back.
I dont think its the end of the world, even if I would really love better options.
Offensively? He could be a key man, more so than any of the other options.
Liverpool playing on the break, high fullbacks etc - who would you want getting the ball around the half way line on his flank with space to pass into?
Trippier can be absolutely deadly from those positions, and they are the sort of chances/half chances that will be presented. Him getting a turn over and suddenly Son in space with a run on VVD...
Sanchez/Aurier/Dier/Whoever - none of them would match up to Trippier in those areas.
Sissoko having to help out with RB leaves a massive hole in the centre of the park.
His passing has also been a liability at times and his crossing as well.