Last night doesn't prove anything. The fact is that we have had a horrendous dip in form over the past 2 months, most likely because of lack of rotation and tiredness. Winning 2 games in a row with the same team doesn't really change anything. If fitness issues were rubbish, I could argue that we would have never gone on a bad run.
Most likely due to injuries, a lack of confidence, and speculation that our manager was due to leave the players behind undermining the confidence in him.
I fail to see how we can be somehow tired in mid-season, yet those same players that apparently were poor because they'd always been picked when fit (Walker, Kaboul, Bale, Modric, Ade) have now given very good performances in some of the last 2 games, when they haven't been rotated, have continued to always be picked...and it's later in the season.
The tiredness issue is an excuse, is something people easily jump to so they can rationalise something. When we played Chelsea at their place, they were apparently tired. Then they have 3 massive games in the space of 6 days with us and Barcelona, and win them all. They are somehow not tired then. Then last night they lose to Saudi Sportswashing Machine and I've read some reports that they were tired again. Or the fact that when Barcelona lost to Madrid they were apparently more tired than Real, but then when Madrid lose to Bayern on pens some reports say they 'looked tired'. It's so, so stupid.
Maybe when teams lose games it's because they weren't that good? Maybe they were outclassed tactically? Maybe their confidence was low? Maybe they were off form? Tiredness as an excuse just does not make sense when teams fluctuate with good to bad results with no correlation to what time of the season it is.
Form and confidence have way bigger effects. MK made an excellent post on it yesterday. At the top level, these guys are all hyper competitive, highly motivated and well prepared by their elite coaching teams. It's confidence which is intangible, can't really be prepared for and can't just be 'given' to a player. It comes from success, and it breeds a state of mind where good play flows naturally.