"We have to win them (the November Tests). We've felt we have been at that level but haven't delivered on that," explained the Wexford man.
"We probably haven't had a great last 10 to 12 internationals - a lot of injuries, a lot of transitions, a lot of change. Just things didn't go our way, whatever the reasons.
"It's a clean slate now, but at the end of the day we have to win now. We have to start winning and we have to win all our three matches.
"There is the change in coach, there is the new set-up, but we actually have to win and start rebuilding belief in the Irish team and all three teams (Samoa, Australia and New Zealand) are ahead of us in the world rankings."
Having played under Joe Schmidt at Leinster, the three-time Heineken Cup winner believes that has helped with the transition into this new national regime.
Commenting on Schmidt's Ireland set-up, D'Arcy admitted: "It is completely different and it was always going to be that. Joe was a very different coach to anything we have had before. If we hadn't been coached by him (before at Leinster), we would be just as shocked as anybody.
"But once you get over the initial shock and demand for high standards you realise it is for the best and you have to hit those standards if you want to play."
"He's just being a constant voice. He demands that everything is done right. If you are running a line that you are running empty, he doesn't want you running with your hands down.
"He's going to pick on you as much as he's going to pick on the guy that is actually getting the ball.
"It is definitely a learning curve. The good thing about being in national camp is you are with the best players and they are hungry to learn new things and the learning curve is very sharp.
"Two or three sessions everyone has it and then you build on that. There has been a very steep progression from Monday but nothing that the lads can't handle."
The one remaining piece in Schmidt's puzzle centres around who will get the captaincy role, with O'Connell and D'Arcy's Leinster colleagues, Brian O'Driscoll and Jamie Heaslip, among the leading contenders.
D'Arcy believes the senior players will continue to show leadership no matter who is chosen as Ireland captain.
"There is a good core leadership group. Without naming names, I'm pretty sure everybody here can figure out it is going to be one of five guys," said the 33-year-old.
"Whoever it is, it's irrelevant to everybody else as the core leadership crew is there. People respond to them anyway. That will be crossing the t's and dotting the i's. It doesn't make a massive difference."