Barcelona endured a humiliating 4-1 defeat in Celta Vigo on Wednesday with many shocked by the result.

Barcelona started the match with most of its starting lineup. Gerard Pique, who had to serve a ban for an early season red card in the Spanish Super Cup, made his return. With the exception of Ivan Rakitic sitting on the bench in place of Sergi Roberto, the lineup is what you would expect from Barcelona in a top level competitive game.

Yet the team was outplayed for 90-plus minutes and wound up put to the sword by a team that is now atop the league standings.

One could pin it on a number of factors but the reality is that Barcelona lost this game on its right wing.

In other words, Dani Alves was the main culprit on the team.

The offensive minded Brazilian is known best for his offensive forays as well as his inability to track back quick enough to defend. A year ago there was much concern about the loss of speed damaging Alves' game overall. At 32 it continues to be a concern and his output this season has not ailed those worries.

In this particular match he was caught out constantly. He looked overwhelmed by the threat of Nolito, who put up a goal and an assist, and he relied constantly on his teammates to bail him out.

It seemed clear why Sergio Roberto was throw into the fray by Luis Enrique.

The young Spaniard was not really able to do much offensively, but he was certainly there to back up Alves. Roberto had been deputizing for Alves at that position for a few weeks. He is probably not the man Enrique should go to war with on a weekly basis, but it is clear that Alves may no longer serve that purpose in the long run.

Jeremy Mathieu also continued to prove that his rapid decline is approaching and had a poor game on the left side of the pitch.

Aleix Vidal is likely the one Barcelona is awaiting to claim that spot on the right from Alves, but he will not be around for another four months, leaving Blaugrana to worry about Alves and his diminishing returns on the right flank.