What exactly happened in this tournament? Anand won 3 games, drew 2 and lost 1.
The wins were nice enough, but they were not against Carlsen level opposition. Let's go through them one at a time:
Round 1: Anand gets a fabulous opening in the KID against Ponomariov, and pretty much wins easily. Along the way he misses a winning line (18. Qxd5 instead of 18. Nxd5). Carlsen would be very unlikely to go for an opening like this against Anand, so the game is virtually irrelevant.
Round 2: Simply put, Vallejo Pons plays horribly against Anand in this game, making 2-3 horrific mistakes. The most egregious is 26. Nb5 (26. f3 looks pretty normal), simply allowing black to kick the knight back with 26....a6 and play 27...Ne4, trading off the bishop on g3 and winning the c7 pawn. The chance of someone like Carlsen doing anything like this are quite low.
Round 3: Aronian draws pretty easily with the black pieces
Round 4: Once again Vallejo Pons plays a game much lower than his strength. It's rare that you'll ever see a 2700 player lose a game so easily.
So at this point Anand is 3.5/4, but the problem is none of these games have anything to do with the type of chess he will encounter when he faces Carlsen. But in the last 2 games....
Round 5: A solid game in which Anand draws quite easily with black.
What happened in this game in Bilbao? Aronian was minutely better, but Anand certainly should have been able to draw it, yet he failed to do so. It comes down to one simple point:
If Anand wants to be world champion, he must draw these positions.
Instead, he made small inaccuracy after small inaccuracy, until Aronian was able to win the game.
So yes, on paper it may look nice that Anand won the tournament, but in reality, it casts a poor omen for the former World Champion. The only game that has any serious relevance to what might happen when Anand faces Carlsen is the one game he lost.
Everyone knows that one of Carlsen's main weapons is his ability to grind down opponents in virtually equal positions, and the one chance Anand had to show that he would do better at defending in these positions, he failed in the same way that he failed in the 2013 Championship Match.
So while I do believe that Anand has some chance to win this match, this tournament victory was not a bright and shining achievement for the contender. I would say it was the exact opposite, and if Anand cannot fix this problem of defending very slightly worse positions, the rematch is going to be just as much of a nightmare as the first match was.