He was always a strange signing.
A player who is not comfortable in possession, can't pass, has poor anticipation and composure, then there's the language barrier. Doesn't scream Arsenal player whatsoever so what possessed the club to sign him is anyone's guess.
Holding looks years ahead of him despite being five years younger and only just making the step up to PL level. Should be moved on at the earliest opportunity and have his game time given to Holding.