Liga champions Barca aim to add steel to youthful flair
With teenager Lamine Yamal and Raphinha shining in attack, the Catalan giants proved an irresistible force as they claimed a domestic treble.
However the German coach's high-pressing defensive line sometimes left Barcelona high and dry at the back, even as it made for frequently gripping, end-to-end matches.
The team's 7-6 Champions League semi-final aggregate defeat by Inter Milan was a prime example of the risks inherent in their set-up.
"For me, it's not always fun, sometimes I really suffer a lot," admitted Flick in May after Barca beat rivals Real Madrid 4-3 in a wild Clasico battle to move to the brink of the title.
"I'm really happy with what we are doing (in general), and of course, football is a game of making mistakes. Hopefully, we can make things better and make fewer mistakes."
The coach made a pledge before the summer break.
"I know that we have to improve (defensively) and we will do it next season," vowed Flick.
Whether Barca can maintain the same verve in attack is up for debate even before any defensive considerations.
Raphinha, 28, had the best season of his career, which will be hard to repeat, while striker Robert Lewandowski turns 37 later in August.
Yamal, who has taken former Barca great Lionel Messi's hallowed number 10 shirt, turned 18 in July and is his team's greatest hope in the months and years ahead.
Limited spending power
While Real Madrid have been able to spend over 172 million euros ($200 million) on new arrivals Trent Alexander-Arnold, Dean Huijsen, Alvaro Carreras and Franco Mastantuono, as well as hiring Xabi Alonso as coach, Barcelona's poor financial state means their activity in the transfer market has been limited.
The Catalans believe their youngsters like Yamal, centre-back Pau Cubarsi, 18, and midfielder Pedri, still only 22 despite his experience, will continue to grow and improve.
They brought in Marcus Rashford on a season-long loan from Manchester United to try and revive the English attacker's career and reap the benefits of his huge potential, giving Flick more quality to rotate with.
Barcelona did make one important permanent signing this summer in Espanyol goalkeeper Joan Garcia, improving arguably the weakest area of their team.
Wojciech Szczesny filled in admirably after coming out of retirement to replace the injured veteran Marc-Andre ter Stegen last season, but is expected to take a reserve role behind the new arrival from Barca's city rivals.
Garcia is in line to start as Barca kick off their campaign at Mallorca on August 16.
Another hope for the champions is that the return to the Spotify Camp Nou strengthens them.
While the Olympic Stadium on the city's Montjuic hill has proven a pleasant stand-in for the past two seasons, it lacks the atmosphere and grandeur of Barcelona's traditional home.
The Catalans plan to return there for the fourth league game of the season after the first three are on the road, against Valencia on September 13 or 14.
However Barca's entry date has been pushed back numerous times, initially planned for November 2024, and there could be further disruption.
Regardless, barring disaster Barca will be back there by the time they host Real Madrid in May 2026, with that game potentially decisive in the title race.
Given Flick's side started last season as underdogs to Madrid, that they are favourites to retain the title this time around cannot be taken too seriously.
The key may be whether Flick is able to set the team up in a sturdier way without losing any of their attacking edge.