The one situation that could get worse for Barcelona next season

There's little use in denying it. We're "Game of Thrones" buffs over here at FC Yahoo. But we won't bore you with yet another recap or think piece. We have, however, been pondering whether Barcelona is more like the Targaryens or the Lannisters.

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Both are old dynasties that just refuse to die, houses that face all manner of difficulties yet somehow remain powerful and very much in play for the throne – trading on little more than their good name.

Barcelona, likewise, ought to be in much worse shape than it really is.

It's in the midst of all manner of kerfuffles. Lionel Messi's tax evasion case. Neymar's transfer fee misrepresentation investigation. President Josep Maria Bartomeu's accelerated elections this summer, as part of the fallout of the Neymar case (he succeeded Sandro Rosell, who resigned). The two-window transfer ban. Stylistic conflicts between the players and manager Luis Enrique for first two-thirds of the season.

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Yet Barca won La Liga again this season. It wasn't a stroll in the park, exactly, but since reclaiming first place in March, they didn't relinquish it again. On May 30, the Copa del Rey final with Athletic Bilbao awaits. And on June 6, Barca faces Juventus in the Champions League final.

In spite of all these difficulties and – of course, this being Spanish soccer – "crises," Barcelona could win the treble this year. It would be just the second in the club's history. This, in other words, would be up there with 2008-09 as Barca's best season ever – by that measure, anyway.

Messi has rightly gotten a great deal of the credit for this. For becoming an even more influential player by involving himself in the buildup. For making better use of Neymar. For finding a way of involving Luis Suarez optimally.

But as trophy season winds down in the next few weeks, and, absent a Euro or World Cup, our collective gaze shifts to next season. Can that dynasty survive for a while longer? (For those of you counting, going back to that 2008-09 season, Barca has now won five league titles in seven years and could add a third Copa del Rey and a third Champions League.)

Barca deserves the benefit of the doubt by now, especially when you consider that this run now counts no fewer than four full-time managers who have been in charge. That transfer ban, more than anything, could become problematic, though.

The Blaugranas were able to set their goalkeeper depth right last summer – before the transfer ban kicked in – with the signings of Marc-Andre Ter Stegen and Claudio Bravo. They shored up their midfield depth with the savvy signing of Ivan Rakitic and the return from loan of Rafinha. In Suarez, they completed what could one day be remembered as the greatest striking trio of all time. So the departures of Alexis Sanchez and Cesc Fabregas were quickly forgotten.

What Barca did not address, however, was the back line. Well, that's not entirely true. They actually bought three defenders. Jeremy Mathieu and Thomas Vermaelen were brought in from Valencia and Arsenal, respectively, at great expense. Douglas was signed from Sao Paulo.

But the defense remains Barcelona's primary weakness. The numbers are deceptive here. If it keeps the clean sheet in its final league game against Deportivo La Coruna on Saturday, Barca will have conceded just 19 league goals in 38 games – that's one every other game, and 10 fewer goals than "defensive specialists" Atletico Madrid, which conceded the second fewest. And it has given up 10 goals in 12 Champions League bouts – three of which came in the semifinals second leg against Bayern Munich.

Yet this team has often looked wobbly in the back, particularly on set pieces. It's just that they so dominate most teams, hogging possession and keeping play in the other half, that few opponents get around to doing a lot of attacking. Against a proper team, Barcelona have at times looked quire vulnerable in the back.

That might only get worse next year, since it can't sign any reinforcements.

Of the five defenders who were regulars (25 starts in all competitions or more), only Gerard Pique and Jordi Alba are indisputably in their prime. Javier Mascherano will turn 31 before next season and is still better in midfield. Mathieu turns 32 in October. Dani Alves just turned 32 and, even though his influence has waned considerably in recent seasons, will be sated by the fat new contract the club has no choice but to give him. (Woe onto Barca if it fails to, considering what the alternatives are.)

Among the backups, Adriano has made the least appearances this season in all his time at the club; Martin Montoya and Marc Bartra are young and limited; Douglas barely played; and Vermaelen didn't play at all, with yet another injury.

Let's be honest. Alarm bells aren't exactly ringing in Catalonia right now. And if Barcelona does develop deep defensive problems, the January transfer window will likely bail them out – even if prices tend to be very inflated then. But the situation with the back line bears watching.

Unless Barca gets hold of The Mountain. Or a dragon.

Leander Schaerlaeckens is a soccer columnist for Yahoo Sports. Follow him on Twitter @LeanderAlphabet.