If it has its a pic of the rear mech on my bike. Im having issues where it appears that once it starts to get clogged it doesnt shift, resulting in me having to increase tension on the ride. Cables have all been changed, and setup correctly. But it is still happening. On the basis that it is due to cloggage im trying to think of a way of minimising the mud off tyres.
Issue is clearance at the mech to tyre, was going to try and fashion something with one of those neoprene fork guards you can get but not sure if it will work.