several january signings have failed to impress in the premier league .
chelsea winger juan cuardrado has barely played since fiorentina move .
wilfried bony has scored one goal after leaving swansea for man city .
qpr tried to send mauro zarate back to west ham before he flopped .
callum mcmanaman has failed to show his wigan form at west brom .
benfica 's filip djuricic has struggled with injuries at southampton .