Millwall boss Kenny Jackett felt his side had failed to click in the final third as they ended their campaign with a 1-0 defeat at Barnsley.
Reuben Noble-Lazarus' first goal in senior football gave the Tykes their best finish since returning to the Championship, but Jackett insisted his side should have taken something.
He said: "I am disappointed with us going forward; I thought our shooting was very poor.
"For long spells we had a hold on the game. I am disappointed that our players can do better than that. We didn't work their keeper and we got what we deserved.
"We didn't show enough quality and didn't take any of the good opportunities we had.
"We want to win every game, but for a club the size of Millwall we've had a very good season. To finish ninth in the Championship is a great achievement because there are a lot of good teams below us."