Plymouth Argyle boss Peter Reid says inexperience was to blame for his side's 4-1 defeat by Rotherham United at Home Park.
After going ahead through debutant Will Atkinson, Argyle capitulated as Gareth Evans and Adam Le Fondre both scored twice for Rotherham.
Reid told BBC Devon: "We took the lead but then the wheels came off.
"I think it was a bit of naivety and inexperience but it's a hard league and we've got to learn."
Of Plymouth's starting XI against Rotherham, only captain Carl Fletcher, defender Stephane Zubar and midfielder Simon Walton were at the club last term.
Reid continued: "I don't want to make age an excuse, because when you make it an excuse it's an easy way out for the players.
"Yes they are inexperienced and yes they will make mistakes,but it was too easy the way they got through us, so we need to tighten up.
"It is a terrible result but we weren't three goals worse."