The Sunderland striker has failed to score in his last six matches for the province and is stuck on 35 goals in 75 international appearances.
Healy did not even make the bench for his club at Stoke last weekend and that has led to further question marks over his form and fitness.
"It is silly really that people are writing him off. It is a bit embarrassing sometimes that a lot of people run him down," Evans told the BBC.
"When you look at David's record he is a hero and still young-ish. He is going to be scoring goals for Northern Ireland for many years to come."