Chris Boyd admits Saints produced far from a great performance at the Ricoh Arena on Sunday afternoon.
But the boss praised his players for keeping their composure and sticking with it until the end as they snatched a dramatic 15-14 victory against Wasps.
The black, green and gold struggled to get any sort of dominance for long periods of the game, giving Wasps the chance to go 14-0 up.
But a James Grayson penalty kick-started the Saints fightback, and tries from Taqele Naiyaravoro and, after the clock had hit 80, Mitch Eadie proved key.
Grayson converted the last-gasp Eadie score to seal Saints' second Premiership Rugby Cup victory in as many matches.
And Boyd said: "I'm very pleased that we stuck to what we were trying to do but in all honesty it wasn't a great performance.
"We were probably a little lucky to come away with the points, but for us the PRC has been about our young guys learning.
"Whether we won or lost that game is immaterial. The most important thing is that there were some really good lessons for some young guys.
"They will get much more out of this game than they did putting 50 points on Bristol last week."
Saints had started well against Wasps, but after spurning promising early positions they fell behind.
Marcus Watson scored for the home side on 14 minutes and Wasps were unfortunate not to go in with more than the 7-0 lead they held at the break.
"I said to the boys at half-time that we just played with no passion and enthusiasm in the first half and you're never going to get your role clarity, skill execution and decision making right if you're not dominating anything," Boyd said.
"We had 18 phases in a row where we soaked it up and finally Ben Franks got a bit angry and dealt with someone and the game changed just a little bit.
"We just weren't dominant in the contact area to control the game."
But Saints finally got to grips with things late on, introducing several debutants during the second half.
And Boyd added: "There were seven or eight guys playing for the first time for Saints so there were a lot of young guys.
"I can't really single anyone out who was dramatically outstanding, but it's exciting to have these guys coming through.
"The nice thing in the young group was that we stayed composed and stuck to what we were trying to do."