armchair quarterback

Noun

 * 1)  A person who watches sports on television, typically American football, who often verbally suggests plays or critiques the players and coaches.
 * My dad is such an armchair quarterback; he recognizes every bad decision the coach makes as soon as the play is over and he knows whether or not it worked.
 * 1)  A person who criticizes something in which they are not involved and lack expertise.
 * 1)  A person who criticizes something in which they are not involved and lack expertise.