London Welsh assistant coach Gordon Ross admitted the chance to beat Gloucester had got away from his team after they suffered a 10th straight defeat.
Six penalties from Aled Thomas condemned the Exiles to an 18-9 LV= Cup loss at the Kassam Stadium, with three penalties from Will Robinson being the only response.
"The game was there for the taking but we didn't have the level of execution and there is a feeling of disappointment in the changing rooms," said Ross.
Neither side possessed the creativity to score a try with nine penalties being the sum total of the action on the scoreboard.
There could have been further penalties but Welsh surprisingly declined to take three kickable attempts in the second half, which proved to be the wrong call.
Ross added: "They were on-field decisions to go for the line-out and drive over but we lost a crucial line-out and they broke away to kick another goal."
"Ill-discipline cost us in the first half and prevented us from building a platform.
"However if an outsider came and watched us train, they would see our standards are very good but unfortunately we are not transferring these to the actual games."
Gloucester assistant coach Nick Walshe was delighted with his inexperienced side's performance.
He said: "We knew it was going to be a tough game as they had quite an experienced pack and we had four debutants in ours.
"The young boys were struggling with cramp with 20 minutes to go as they are not used to playing at this level but the way they defended in the second half was magnificent."
Walshe also paid tribute to Thomas, whose goal-kicking secured the victory.
"Aled was fantastic today," he added. "He controlled the game, kicked his goals, apart from one long-range effort, and led the boys well in his first game as captain."
With this win, Gloucester maintained their interest in the competition with two home games against Ospreys and Harlequins to come in the new year.
"We were really disappointed to lose at Exeter last weekend," added Walshe. "Today's win gives us a chance but Saracens have won two from two in our group.
"It's an important competition for us and we want to keep the momentum going as players should always have pride in playing for the Gloucester shirt."