Dembele and Coutinho still need to adapt to Ernesto Valverde's tactical demands

Barcelona manager Ernesto Valverde did not hesitate to act, taking off Ousmane Dembele and bringing on Denis Suarez. A few minutes later, Philippe Coutinho was also sacrificed for the introduction of Paulinho.

The consequence – although whether it was as a direct result of the substitutions is uncertain – was that Barca re-established control of the game, and ended up running away with a 4-2 victory as Lionel Messi took over.

And it just went to show that Valverde has some big decisions to make as he formulates his plans for the next season.

In an attacking sense, Dembele and Coutinho had both enjoyed decent games. They combined neatly for the opening goal, netted by the latter after an adroit pass from the former, and proceeded to regularly threaten the Deportivo defence with Dembele’s pace and direct running and Coutinho’s trickery on the ball and long-range shooting.

But they were both weak defensively, leaving full-backs Nelson Semedo and Jordi Alba dangerously exposed. And when Deportivo took advantage by grabbing two goals to level, it was clear from Valverde’s reaction whom he blamed for the unwanted turnaround.

Dembele, in particular, clearly does not have the full trust of his coach – evident most starkly in the fact that he was left on the bench for all but the final few minutes of the Champions League quarter-final against Roma. Don’t expect to see him start against Real Madrid next weekend.

The 20 year-old, clearly, has time on his side. He is still extremely inexperienced and hasn’t had anywhere near enough time to learn the intricacies of a structured team system. He is hugely talented, that much is clear, but the majority of his work is instinctive, off the cuff.

There’s a time and place for that, of course, and Dembele should become a major asset to Barca for his ability to deliver something different – a piece of skill or a flash of pace to destabilise the opposition defence and create openings for Messi and Luis Suarez.

But he also has to learn how to defend, how to avoid conceding possession cheaply, when to attempt a piece of flamboyant skill and when to settle for just keeping simple possession. If he doesn’t, his time will continue to be limited.

Coutinho is a different matter. He is a much more tactically aware player, shown by his ability to deliver good performances in a wide variety of roles since he joined the club.

However, he does not have many defensive instincts and plays primarily for the final third, where he has great ability to either create a chance with intricate passing or taking on a long-range shot.

At Barcelona, he’ll have to do a lot more than that going in the other direction, especially if he is ultimately to take the chance of becoming the heir to Andres Iniesta – whose quality of defensive work is largely under-appreciated – in the centre of the pitch.

Other than the occasional exception like Sunday night, Barcelona have not won this title by winning games 4-2. They boast the second-best defensive record in the league and established their unassailable gap at the top of the table with a series of clean-sheet victories during the autumn and winter.

Valverde is that kind of coach. He is cautious, conservative, and balanced. He will not go out gung-ho for victory in the bullish belief that however many goals his team happens to concede, they will always be able to score one more.

With Messi the undisputed leader, he already has one player who is effectively a passenger in defence. He cannot afford any more, and Coutinho and Dembele – however much money they cost – will have to massively improve their levels of defensive commitment before they can be guaranteed a place in the team next season.