There's been a lot of criticism of Quintana in the last week and a lot of people over-reacting to that criticism. I think you have to look at how his career has unfolded to understand why people have this emotional reaction to him, like they feel betrayed.
The first superstar moment from Quintana came in the 2012 Dauphiné. Sky Train v1.0 had smothered every one-week stage race they entered all year, and none of the GC guys had any answers, except to hold on and try and steal a few seconds on the descents. Enter Quintana who floats away off the front 5km from the summit of the Joux Plane.
Fast forward to the 2013 Tour. Froome is now the caboose of the Sky Train, but he's a way better climber than Wiggins was. Quintana, there as backup for Valverde, attacks 34km out on the first mountain stage - he's reeled in but is applauded for the ballsiness of the move. People are fearing another USPS scenario of one team utterly dominating for a good chunk of the next decade. Obi Wan Quintana is our only hope. He outclimbs Froome in the last week and comes second on the podium and easily picks up the white and polka dot jersey.
So there's a narrative in place at this stage. Quintana is going to save us from boring stages and marginal gains and management speak. Even more romantically, he's going to avenge the lost generation of Colombian climbers, the ones who looked at the end of the 80's like they were going to change cycling, but who, as small guys with naturally high Hcts, were no match for hulking Frankensteins like Riis who were transformed by EPO.
So what happens next? He wins the 2014 Giro, but the defining moment of the race is the polemica on the Stelvio descent. In the 2015 Tour de France he seems unwilling to attack Froome for most of the race in case it puts Valverde in difficulty. Even when Froome is clearly in difficulty in the last week he appears content to wait for Alpe d'Huez. He puts a chunk of time into Froome but it's too little, too late.
The 2016 Tour is also disappointing. He's not in great shape and he appears content to move up the ranking through attrition, although the crosswinds probably hurt him more than any other GC rider. He wins the 2016 Vuelta, although it's Contador that kicks off the crucial move to crack Froome.
Now in 2017 another podium in the Giro that could have been more - he had everything perfectly set up for a big attack on the Stelvio stage with three men up the road, but he was content to just mark his rivals even on terrain he knew suited him much better than the race leader.
So we have someone people assumed would be winning GTs with panache, but who instead appears content with podiums much of the time, who's willing to play a percentages game, who won't assert leadership when he races with Valverde even though he's much stronger on the high altitude multi mountain stages that so often decide GTs.
As LS has pointed out before, maybe his immaculate poker face hasn't endeared him to fans - there's a perception that he has never really turned himself inside out suffering for a win. There's the suggestion that Unzué has coached the panache out of him. And right now it's fair to say that he's by far the least exciting rider out of the Froome/Contador/Nibali/Quintana 'big four' of the last few years. It's not entirely fair on him but people are judging him on not living up to the hype from his breakthrough.