Agreed. Ox needs to be on the right in order to kind of shoebox him into running down the touchline, taking players 9n and crossing into the box. On the left with too many options he ends up trying to do things his technique won't allow him to do like like switching the play with long crossfield balls and limits his abilities to focus on his strengths such as his power and crossing ability.
On the other hand with Bellerin, even on the rigbt he usually ends up cutting back and going infield instead of going on the outside and putting dangerous balls in. On the left not much will change with regards to his attacking play and may even give him more of a chance as he is coming in on his stronger foot.
But with Kolasinac in the team now he should have that LWB role locked so theoretically Ox and Bellerin should be competing for one spot. And for that RWB role I'd rathdr Ox because of the attacking threat he provides.