The Trinidad and Tobago international squandered some of the Latics' best opportunities in Saturday's 1-0 defeat to Everton and now faces a fight to retain his place in the team after the arrival of Victor Moses and Marcelo Moreno at the DW Stadium.
But with neither Moses nor Moreno eligible to make their debut in Tuesday night's FA Cup fourth-round replay against Notts County, Scotland - who finally broke his Wigan duck in the original tie at Meadow Lane - is likely to get another chance to prove his worth and Martinez is convinced the 30-year-old can still be a success at the club.
"His work-rate has been exceptional, as has his link-up play, but his biggest asset is scoring goals," Martinez said.
"At the moment he is creating the chances and getting in great positions and he hasn't been able to score, but it would be a bigger worry if he hadn't been able to create the chances.
"He is a very strong character and he's in a perfect moment of his career - at 30, he's capable of coping with anything that comes his way. I can see day by day he is becoming a stronger and a better footballer, and the goals will come, it is only a matter of time.
"I'm just focusing on him creating chances for himself and creating chances for the others, and allowing us to have that link-up play that is so effective for ourselves.
"I'm not going to judge a player by the chances he misses - I'm going to judge a player by the chances he creates and the overall contribution to the team."