Published Tuesday, 12 June 2012
McClean watched on as the Republic were beaten. (© Getty)
The team were beaten 3-1 in their Euro 2012 opener in Poznan on Sunday.
Sunderland star McClean was left on the bench in the second half as Trapattoni opted to replace left-winger Aiden McGeady with striker Simon Cox.
It has lead to questions over why the promising 23-year-old, formerly of Derry City, did not feature, after being called up on the strength of his Premier League performances.
Speaking to the press at the Republic's Gdynia training base, the Italian manager said: "I was waiting for this question".
He continued: "Remember when you asked me why five strikers? I said Cox is also a winger and he can also play in a three as an attacking striker. Remember when you said this?
"Cox is one of the strikers but also at his club, can play right or left. He is also a striker in fact and in the past, has scored goals.
"Our wingers yesterday were not too often in on goal. I ask you, how many goals has McGeady scored? How many goals has (Damien) Duff scored? They are our wingers.
"You don't remember? Also me. This is important because at that moment, we needed someone in that position who could also score. Remember also against Italy? Remember Cox scored from this position? He's a good player, Cox."
McClean made his senior debut as a substitute in February.
While Trapattoni was prepared to include the youngster in his final 23 for Poland and Ukraine, he appears to remain unconvinced about his level of experience.
The 73-year-old added: "You are friends with James, no?
"I have a duty. It would have been his first [competitive] game. When there are senior, experienced players in this situation, maybe there is tension. You can understand how much more tense a young player can be.
"It's important we give them a quiet opportunity, not when we need their performance under pressure. It's a heavy weight on his shoulders.
"McGeady is one of our best players, and Damien Duff the same.
"His time will come in the future."
The Irish take on holders Spain in Gdansk on Thursday, with live coverage on UTV from 7.15pm.