For me its quite straightforward.
Arnold looked average at best for England youth and it was like a winger playing full back. Hence why Kenny was 1st choice (by a mile).
What were currently seeing is Arnold looking good in a rapid counter attacking team. It suits him. He also has the media praising him as he plays for the RS and they exaggerate literally everything.
Kenny has all the attributes to become a top class full back. MOTM in games at CB/RB/RWB for England youth and sometimes looked a few levels higher than anyone else on the pitch.
Coleman has been average this season...Kenny should get a start against west ham and id be more surprised if he didn't keep the shirt than Coleman getting back in.
We will see the difference 1-1 in the coming seasons where Richarlison will absolutely school Arnold...Yet Kenny will grow as a top all rounder -- like Neville.
As for Holgate, its totally bizarre what happened to him after the Derby. Hes now had no preseason and I hope Mina is starting soon to give Holgate a breather. This season I want him to be pushing Zouma out by the last few games...its about gradual development for him now to be classed as a starter or in the top 3 at the club. Gomez was class for England youth and I wanted us to sign him...however in top form ive seen nothing from him which is comparable to when Holgate is at his best...again, a case of a player suiting a team and system and being media hyped.
Btw calling Klopp 'der bestest coach in der wurld' is nothing short of a joke. Its kamikaze football spending hundreds of millions of pounds with what to show for it...nothing. The guy is a choker.