English for Today by Ganiu Abisoye Bamgbose (Dr GAB)
OF or OFF?
Your observation is wide ~off~ the mark (nonstandard).
Your observation is wide of the mark (correct). If something such as a claim or estimate is wide of the mark, it is incorrect or inaccurate.
His criticisms are way ~of~ the mark (nonstandard).
His criticisms are way off the mark (standard). Although the idioms in 1 and 2 mean the same thing, the prepositions in them should not be mistaken.
Wash your hands ~off~ the matter (nonstandard).
Wash your hands of the matter (standard). If you wash your hands of something, you intentionally stop being involved in it.
GAB
Interesting