The current holders are favourites to defend the trophy and become the first nation to win successive European Championships and three straight major tournaments.
However, they squandered a number of goal-scoring opportunities during the 1-1 draw with Italy in the Group C opener, with manager Vicente del Bosque opting to field six midfielders during the clash with the Azzurri.
The Spaniard is expected to utilise either Fernando Llorente or Fernando Torres for the crunch clash against the Republic of Ireland on Thursday.
And Martinez has pointed to the 2010 World Cup, and specifically the fitness of Torres leading into the tournament, as to why they altered their style of play.
"I think it's a fair criticism because the truth is Spain mastered possession and control of the game and that is something that is phenomenal to watch and assess, but the truth is in many games the goal-scoring ability is what allows you to win trophies or not," the Latics boss told Yahoo! when quizzed about whether the criticism towards the national side was warranted.
"When Spain arrived at the World Cup, they had a big question mark over Fernando Torres' fitness and up to that point he was the catalyst, the finisher, so that Spanish team had to evolve and find a new way to score goals in the tournament which took a little bit of time.
"But as a team they were patient enough to take their time to be themselves and find a way to win games.
"I'm sure anyone would say the way they played in South Africa was one of the best ways to play the game; completely outplaying the opposition from a technical point of view, being patient and controlling the tempo of the game.
"That is the hardest thing to do on a football pitch."
And Martinez believes the Chelsea striker is the man to replace the injured David Villa, after the Barcelona front-man was ruled out of the tournament with a broken leg he suffered at the Club World Cup.
"I do think that is the biggest concern Del Bosque has at the moment, the goal-scoring capability is a real problem in the Spanish side," he added.
"As you mentioned. Torres went to the previous Euros and he was the main goal-scorer, then suddenly he had some physical problems in South Africa and the team needed someone else.
"David Villa was the one that replaced him but now he's out and Torres seems to be getting back to his best, however it is still unclear what level he will play at in this Euros tournament.
"I think that will be the difference between Spain being able to win the trophy or not; it’s about finding that goal-scoring ability."
For more insight from Roberto Martinez and other leading managers, plus coverage of Euro 2012, visityahoo.eurosport.com
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