One of the things that will be troubling the bright, competitive mind of Ernesto Valverde is whether FC Barcelona currently have an unhealthy or even Pyrrhic relationship with Spain's Copa del Rey?

"Unhealthy" is a concept you can understand quickly: all of us fall prey to things we know we shouldn't do but that feel "irresistible." If "Pyrrhic" isn't a word you use daily, then think of it like this: It means a victory that comes at far too high a cost to make it worthwhile.

Getting the picture?

For the past three years, the boys in Blaugrana have won Spain's Copa del Rey. Kudos. One or two of those finals were truly epic: Against Sevilla, it was the fiendish determination that Gerard Pique & Co. showed to cling on, and then win, with 10 men. Against Athletic Club, it was the spectacle of one of the best goals of Lionel Messi's career.

I'd guess the guys with winners' medals from those showpiece matches are damn proud of how they were won, and rightfully so. But in each of Barcelona's past two seasons, their squad has ended up running on empty by the time April's make-or-break matches come along, victims of the physically devastating six-and-a-half-week period, starting in early January, required to reach the final.

As Thursday's test of fire in the Mestalla looms, against a determined Valencia with nothing to lose -- they have no European tie around the corner and no chance of winning the title -- that could throw the kitchen sink at Valverde's team, Barcelona are already beginning to show those now-annual Pyrrhic effects.

La Liga's leaders might enjoy an imperious position in the title chase; indeed, some will argue vehemently that Barca are uncatchable. However, in all but one of their past seven matches, the "champions-elect" have suddenly looked tired, creatively flat, careless in possession and prone to being caught on the break. They've looked vulnerable.

Against Betis, in Sevilla, Barcelona were genuinely stunning. Strike that one from the list. Once they got a really awful first-half display at Anoeta out of their system, their second half against Real Sociedad was a brutal demonstration of this team's character and quality.

However, in the Copa defeat away to Espanyol, plus subsequent matches against Alaves, Valencia and two more Catalan derbies (one win, one draw), the fact that this group of proven winners are suffering the cost of the assault on the Cup was obvious.

Barca had to dig deep to get a point against Espanyol, but the minor injuries are starting to pile up. Urbanandsport/NurPhoto via Getty Images

Just in case you're not convinced about my premise, look at the evidence.

In 2015-16, Luis Enrique's team played 13 times between Jan. 2 and Feb. 11. That's a match every three days for six weeks. The Catalans were knocked out of the Champions League that April by Atletico and Diego Simeone's side had played three full games fewer in that January/February period. Not only were they vastly quicker and stronger than Barcelona by April, but Los Colchoneros would have enough saved in their tanks to reach the Champions League final.

Back at home that season, Barcelona almost blew it all during that mad first half of April, when the inhuman effort of January and early February put lead in their legs and cotton wool in their brains. Although they would cling on to win the title, Enrique's bedraggled squad lost four out of five fixtures against Madrid, Atleti, Real Sociedad and Valencia.

Last year it was the same story, only worse. There were 12 high-tension, viciously draining matches in only 34 days, an average of a game less than every three days for more than a month. Messi, for example, played all but 27 minutes of that punishing sequence as Barca went for the Cup final and remained competitive in La Liga. Then, immediately after, came a complete Champions League thrashing as Barca lost 4-0 to PSG.

Okay, that result was ultimately a platform for the remarkable 6-1 win that put the Catalans into the quarterfinal, but once there, Juventus clinically stripped them of their chances and their dignity. Just as in Paris, Enrique's players were stumbling around like zombies in Turin, and the blame lay with their brutal, unforgiving Pyrrhic mistress: the Copa del Rey.

Juve in 2016-17? They'd played four fewer games in that killer zone of January and early February. Once again, the rival that was ultra-fresh in April and eliminated Barcelona went to the Champions League final. Take note.

So now, the coup de grace. Let's look beyond the fact that Atleti and Juve, both less drained and less debilitated, not only eliminated Barca but reached the final. Let's glance at Real Madrid.

It embarrassed them to make the administrative error of playing Denis "I'm actually suspended" Cheryshev against Cadiz and getting kicked out of the Kings Cup, but in 2015-16, they played zero Cup ties in January or February.

The benefit? Once Zinedine Zidane took over at the beginning of the year, they hunted Barcelona down to the last game of the title race and were stronger than Atletico Madrid when it really counted during extra time and penalties during that Milan Champions League final.

Last season? Knocked out in the quarterfinal of the national Cup meant three fewer games than Barcelona in that brutal zone, so Madrid had sufficient vim and vigor in April and May to become the first team to retain the Champions League.

It might all serve as a cautionary tale to FC Barcelona ... only it's too late.

Pique isn't the only one carrying the wear and tear of fixture congestion, but the worst is yet to come. Urbanandsport/NurPhoto via Getty Images

Valverde & Co. are knee-deep in it again as we push into February, and there isn't a player in his squad who won't man the barriers at the Mestalla in pursuit of their fourth consecutive Copa final.

However, if Valverde, his fitness guys, his medics and Barca "captains" Andres Iniesta, Messi, Sergio Busquets and Pique (in effect if not in rank) are working out how to not only eliminate Chelsea starting in a fortnight's time but also somehow march their way to the Kiev final, then the first thing that will be discarded -- and violently -- will be the growing demand to know whether the league leaders can go the domestic season unbeaten.

Compared to somehow being fresher than since 2015, when Europe's big games come along, remaining "invincible" in La Liga is a minor prize. In fact, it's a distraction. At the weekend, during what was an entertaining but viciously demanding collision with Espanyol, Barca rescued a point in extremis. Trailing 1-0, playing what resembled water polo amid the little lakes of water in Cornella, coping with one or two brutal tackles from angry rivals and quite evidently verging on exhaustion, Valverde's side fought like tigers for the draw.

"Not today ... not against you lot!" That was patently the attitude exuding from every single player and ever member of the technical staff. But if that kind of attitude -- "I don't care what's around the corner, I'm not yielding a millimetre" -- governs the mind of the coach and the senior players from now until April in La Liga, then it should be taken as almost a given that one of the big guns (be it Atleti or Madrid domestically or Chelsea, PSG or Man City in Europe) will reap the dividends.

Already, the "champions-elect" (is it really all over?) face the prospect that if Yerry Mina plays at centre-back in Thursday's semifinal and somehow gets injured, they'll not have a single fully fit centre-half to face Getafe at home on Sunday, given that Samuel Umtiti is suspended. And we're only in early February.

Mina, Philippe Coutinho and Ousmane Dembele are only beginning their integration with this squad, but already, it looks absolutely vital that they put their shoulders to the wheel pretty quickly.

On which subject, if Barcelona are to yield two (or three!) trophies from what so far has been months of admirable attitude and regular bursts of terrific football, would you bet against them having to rely on a few vital performances from the currently much-maligned Barca B squad to do it?

Stand by your beds, Marc Cucurella, David Costas, Oriol Busquets, Jose Arnaiz and Carles Alena: Barcelona's love affair with La Copa might mean your moment of destiny is closer than you think.