Hernandez was on target twice at the DW Stadium on Saturday as United recorded a 4-0 victory over Martinez’s side.
The Mexican striker had caught the eye of the Latics, but the Premier League strugglers were priced out of a move for the player, who then plied his trade at Chivas de Guadalajara.
“He was a player that went out of our market,” Martinez said, according to The Daily Mirror.
“I think everyone was aware of him when he played for Mexico.
“But obviously he’s a real talent who Manchester United probably captured before he caught the eye of anyone.
“He’s very clever with his movement, tactically impressive and a real asset to United.”
It is thought Hernandez cost the Old Trafford club between £6-8 million upon acquiring a work permit to move to England in May 2010, before the striker went on to impress at the World Cup in South Africa.
Hernandez – nicknamed ‘Chicharito’ – has scored 13 goals in all competitions in an impressive first season in the Premier League.
Wigan, meanwhile, are bottom of the table following West Ham United’s 3-1 victory over Liverpool on Sunday.