Assuming he had it in him to progress at all, not withstanding that, his lack of progress firmly lies at Martinez's door.
Iirc, He made a comment about 'internal goings on' either before or after the Newcastle game, which left Martinez in a poor light...along the lines of 'nobody knew what they were supposed to be doing'.
IMO, post Distins freeze out, given that the wheels were starting to come off the 'brown shoe bandwagon' (Oh yes they were) these comments were, on refection best not said in public.
Martinez not best pleased?...and promptly gave him, (with help from soft hearted Kenwright) the 'new 30K contract carrot' coupled with the 'straight out the door on loan stick'
Then gave him some more stick with a season long loan to Fulham, were he got injured.
Down hill from then.