Toni Kroos and James Rodriguez were expected to improve what was already a formidable side, but the departures of Xabi Alonso and Angel Di Maria have placed insurmountable pressure on the pair to instantly deliver. And while Kroos sporadically showcased the threat he offers from midfield, it's evident that it will take sometime to successfully succeed Xabi Alonso in a deep-lying role. James, on the other hand, failed to influence the match and was considerably underwhelming.
Oddly, Madrid was sensational in the opening 20 minutes. Marcelo was surging forward into advanced positions and combining with teammates down the left flank, and Isco was doing an adequate job of linking midfield and attack; however as the match progressed, the Spaniard's final balls were extremely woeful.
Ancelotti's side took a commanding two goal lead in the opening 10 minutes courtesy of Sergio Ramos and a moment of brilliance from Gareth Bale, but the flattering score line didn't illustrate their dominance. Ramos squandered three legitimate chances to increase Madrid's lead in the first half - taking advantage of Sociedad's woeful set-piece defending - whereas goalkeeper Enaut Zubikarai's nervy challenge with Karim Benzema along with an impressive save to deny Kroos prevented the away side from increasing their lead.
However, there was a sudden change in the tempo of the match following Zubikarai's save on Kroos, a few hints of susceptibility throughout Real's back four. Iker Casillas punched a venomous Gonzalo Castro cross away from danger, while Ramos sacrificed his body to block an Esteban Granero shot from point-black range - that play also stemmed through Castro's delivery into the box.
Madrid's relentless wave of attacks decreased as they rushed into Sociedad's third and conceded possession cheaply, opposed to patiently creating attacks through ball retention. There was also a sudden lack of invention, guile, and creativity when Madrid sustained possession, and they failed to get runners behind Sociedad's two narrow banks of four.
Likewise, Sociedad also encountered difficulties getting behind Madrid's defence, but they found spaces down the flanks to torment the away side. Alberto de la Bella continuously ran past James, while Xabi Prieto's movement into central areas and half-spaces enabled Zaldua to storm into advanced areas.
Still, all four goals Madrid conceded were preventable, as simple marking mistakes, and mental defensive lapses led to their downfall. Inigo Martinez ran behind Ramos to tap in Prieto's flick-on header at the near post to trim the lead to one goal.
Sociedad's second goal signified Madrid's difficulty coping with de la Bella's forward runs and David Zurutuza's movement. Zurutuza drifted centrally and flicked a pass into the left channel for De la Bella - who received plenty of space from Dani Carvajal- and the former ran behind Kroos to direct the left-back's cross past Casillas.
Real Madrid's attempt to attain control of the match proved futile in the second half. Isco couldn't connect with his teammates when Madrid broke from midfield, and the away side's narrow attack was laboured. Ancelotti reluctance to make an early substitution was quite peculiar, whereas Jagoba Arrasate altered the tempo of the match by introducing the Carlos Vela and the nifty Sergio Canales.
The third goal, scored by Zurutuza, exploited Madrid down the flanks once again, as the Sociedad winger's movement was equally terrific. Canales overloaded the right flank to combine with Prieto, and neither Marcelo nor Isco tracked the latter's run, while Zurutuza ran across Carvajal to direct another cross past Casillas. Vela joined the goal-scoring festivity nine minutes later, and while there was a hint of handball in the buildup, Pepe's marking on Vela was shambolic.
Ancelotti's side pushed forward in the latter stages of the match, improving once Sami Khedira was introduced as the German's direct forward runs offered Madrid another element of attack in midfield.
"It's not easy to assess this match. We scored twice. For 30 minutes we were very good," Ancelotti said.
"The rest of the time we were bad and it's hard to imagine we thought the game was over."
The sales of Alonso and Di Maria provides reduced time for James and Kroos to adapt, but it also increases Khedira's significance to the squad, as his combative style will be required when Madrid face sterner tests on the road. Nevertheless, Arrasate's double-change was also pivotal, as Vela's pace and Canales' creativity created additional issues for the away side.
While Madrid failed to control the match or create legitimate chances subsequent to taking a two-goal lead, the manner in which they conceded all four goals - poor marking and defending from every member of the back four, along with Isco and James' reluctance to protect their full-backs - was the decisive factor in a disappointing display from the reigning European champions.