McCarthy is grateful to Trapattoni for giving him his international chance.
McCarthy told the Daily Mail: "I think if you're a young boy you need to be patient. I've had to be patient.
"You can't take a huff because we've got a lot of quality players in the squad. It's good for us to get the chance and when you get your chance you go and try to take it and try to stay in the team but it's not easy for the boss.
"You can't just blood all young kids. It's not an easy decision to make and it's not easy for young kids to just get thrown in at the deep end. He's brought in a few now and obviously the press and everyone has been getting on, the fans want young blood.
"You've got to be patient, you need to take your time. I think that's what he's done, he's bedded us in nicely and he's starting to give more chances. But to be honest it's not about the young boys. The experienced boys help you through the game and you can't just go and play 11 kids out there, you need experienced pros.
"It worked well against the Faroes and even against Germany, for the first half-hour I thought we coped well with it and then obviously the goal and it just went downhill from there. The most important thing is we're back on track now."