This illustration shows how the foot is out of A/P (anterior / posterior) balance . As you did mention arthritis ,the foot being forward of center of articulation could be the cause of your horses recent lameness .
As always it is hard to tell by a picture . It is always better to have it in your hand to make a better assessment. The Hooves do look like they are in good shape so I wouldn't go dogging cussing your farrier. Just a simple nice conversation and agreement and everyone involved is happy 989898.jpg