Karim Adeyemi opened his account for the club and Jesse Bisiwu came off the bench to score twice as Barcelona finished their summer schedule with an emphatic victory in Switzerland, a result that leaves Flick encouraged heading into the LaLiga opener against Elche, with Anthony Gordon also making his first appearance since arriving at the club this summer.
Speaking after the match, the head coach called the contest valuable preparation for the season ahead.
"It was a good test for us, and we're already starting to think about the first match against Elche on Sunday. It's not an easy job to manage, there are a lot of players who have only recently joined up with the group."
Asked about returning to Basel for a special friendly, Flick kept his answer brief: "Yes, I know. Happy to be back here."
The German turned his focus to the club's business in the closing days of the transfer window when pressed on the market, while stressing that his priority remained on the training ground.
"We'll see this week, maybe something's still missing. The most important thing is how we're working. There's intensity and quality in training. I can see the team raising its level and that's the most important thing. We have to work hard to maintain last season's level."
Flick has been shaping his squad throughout preseason around a mix of established names and emerging academy talent, with several new arrivals still bedding in after later returns from international duty. Karim Adeyemi and Anthony Gordon both featured in the win, with Adeyemi opening the scoring in the 34th minute after a Raphinha assist, before Basel's Doucouré levelled just before the break.
Barcelona pulled away in the second half, with Hamza Abdelkarim, Lamine Yamal and a Bisiwu double completing the scoring in Switzerland.
The head coach's comments come with the transfer window still open and Barcelona continuing to work on incomings before the deadline, even as attention turns fully towards Sunday's league opener. Flick has previously made clear that adding a recognised centre-forward remains a priority before the window shuts, having used Raphinha as a false nine against Basel in the continued absence of an out-and-out striker following Robert Lewandowski's departure.
Barcelona finish their preparation having tested a variety of attacking combinations, and Flick will now have a full week on the training pitch to fine-tune his side before the visit of Elche opens the defence of last season's LaLiga title.