The most fundamental tenant of headers and volleys was precisely that; to win it had to be a header or volley.
Every so often that one lad would come along and attempt the surreptitious self-assist. A failed cross or motionless ball chipped up to themselves and struck on the volley. It's a moral grey area of the game. TheFA.com website, which actually lists the 'standard rules' of the game, stat 'only goals score with a header or volley count' but do not clarify this particular technique.
Nevertheless, Radamel Falcao was not playing headers and volleys but an actual professional football match. Monaco are currently 2-0 up against Montpellier in the Coupe de la Ligue thanks to an audacious Falcao goal.
It's not as sweet a strike as it should be but props for the attempt in the first place.
Falcao followed it up with another much standard finish, which currently wouldn't score him any headers and volleys points.
The resurgence of Falcao after his disappointing spell in England is interesting. The 31-year-old already has 25 goals this season and peeking right in time for the World Cup. With a group of Poland, Senegal and Japan, the Columbian could well be a dark horse for the Golden boot in Russia this summer.