Scrum-half Conor Murray acknowledged that Ireland were always fighting a losing battle after making a slow start in their 32-20 home reverse to England.
Ireland won the Six Nations Grand Slam last year, but they began the new campaign in disappointing fashion as Jonny May and Elliot Daly scored early for Eddie Jones' visitors in Dublin.
Although Cian Healy responded for the favourites, Henry Slade crossed twice in the second half to secure a bonus-point win for England before a John Cooney consolation try.
Murray felt the game was lost early in each period, describing aspects of Ireland's performance in the opening match as "flat".
"We started slow," he told ITV. "We gave up a couple of soft tries and, against a team of England's quality, you're always going to be struggling.
"In the end, we were chasing it and gave up another couple of soft scores. Our start killed us. You can't come out here and start that slow and expect to win.
"We did steady the ship a little bit and got back into it. At half-time, the chat was good. But then we were a bit flat coming out again, which is not like us.
"It's very hard to put your finger on it but, against a side like England, you can't afford to be flat."