2006: Brain injury, probably too young to get GT result anyway
2007: Obviously lucky to get Rasmussen taken out, but before that it was eerily similar to Nibali's 2019 Giro of giving 3 minutes to who turns out the best climber for free, while also having 2 crucial flats costing him an unkown amount of time. First Tour win, don't think it's a missed opportunity to ride a Tour/Vuelta double.
2008: Giro is what it is. He was consistently among around the 5th best climber on other mountain stages, and who was better fluctuated heavily. Gets screwed out of a very likely Tour win. Wins Vuelta putting time into the #2 on all 4 MTFs. Don't think it's overperforming much if at all.
2009: Best year of his career, only wins Tour + 2 stages. If anything that's underperforming. Giro/Tour double attempts weren't that rare and that terrible back then, and it would've been the golden opportunity for him to do it, unlike later years. Alternatively, could've done Tour/Vuelta and be a massive favorite to pull it off.
2010: TdF win, no stage wins. I think Avoriaz is over stated, he responeded to like 3/4 attacks in succession before Andy Schleck dropped him. I think this also ignores that Contador lost like a minute 20 on the cobbles at the expense of Fränk Schlecks collarbone.
2011: Nothing clutch about that Giro, could have won at least 2 more stages if he wasn't gifting them left, right and centre. Got his TdF chances wrecked by a crash. Without it is anyone's guess. Obviously there were reasons for Giro/Tour in the first place, but if he doesn't go to the Giro he's an overwhelming Tour favorite, as well as probably a Vuelta fave if he decides to go for it.
2012: Obviously only gets to ride Vuelta. TdF would have been somehwat interesting if he'd been able to ride, and fully dependent on in which form he'd have shown up. Fuente De is clutch yeah, but Rodriguez got dropped hard that day and I'm fairly sure Contador drops Purito there if he waits for the final climb. Shoutout to the fact he only won that stage cause he attacked the breakaway before the flat. Otherwise he would've never dropped them.
2013: Underperforms hugely all year. Schedule doesn't really matter, though might have eeked out a podium in Giro if he'd gone there, but whatever
2014: Obviously the Tour everyone wanted to see never happened. One Vuelta win was the bare minimum for how he was riding that year. As the Tour happened, I don't think he woudl've taken the 2 and a half minutes back from Nibali. Nibali was insane himself, the route wasn't that monstrous, and good luck dropping Nibali far from the finish without him catching up on the descent.
2015: Giro win wasn't particularly lucky/overperforming IMO. His level was good, but not amazing, and I wouldn't know if that was because they tried to do a Giro/Tour double. Would've had to ran into some pretty bad odds to lose that one. 2015 Tour is basically a scheduling horror show and he literally got nothing done that Tour, apart from one of his most hilarious attempts to follow Froome on an attack when it made no sense to try on La Toussuire.
2016: Crashed both GTs away. Not even a podium is really poor. Increasing tendency of trying desperately to follow Quintana only to blow up every time. One redeeming moment is burning the Vuelta down and being the kingmaker of that race.
2017: Similar to 2016, except he finished the Tour and just had the random sick (?) day at the Vuelta. Don't think it's that graet to only get one stage out of it. At this stage it's weird to see him fly in the 3rd week of the Vuelta after not showing that level in like 2 and a half years.
Don't think he would've won either Tour in 2016/2017, but IMO there was a non 0 chance and we never got to find out.
All in all, I think he mostly "underperformed" in terms of not riding as many GTs at the height of his power as he would do later. Could also have gotten a little more out of his schedule after he stopped dominating, but then you wouldn't assume/want him to do Giro/Vuelta every year either.
Just by form alone he could've won 5 Tours in a row from 2007-2011 but that's also stretching it a little bit. All in all, I think he was as close to winning more as he was to winning less.