The Chilean scored his first goal for Wigan when he nodded home Shaun Maloney's far-post cross 11 minutes from time.
"I was pleased that they didn't seem like new players," said Martinez.
"They looked like they knew exactly what they were doing.
"Roger (Espinoza) is someone with great energy, which he compliments with a real style in possession.
"Angelo is a goalscorer and to score a goal on your Premier League debut is a great boost for his career."