...and Thomas was also 32 and with a previous best of 15th in a GT, albeit as a superdom. Yes, he'd been good in one-week races, but in his only previous attempt to lead a GT he'd exercised his usual tendency to crash at inopportune times (not his fault on that particular occasion, mind) which helped perpetuate the impression of him as not a GC guy. I thought he was George Hincapie Mk II. I still do, despite that he's actually won a Tour de France now - a former cobbles guy who becomes a climber in the service of a bigger national star, starts scoring climbing results in late 20s and then groomed as a successor despite a lack of real GT palmarès. The real shock with Thomas was more that he turned into a GC contender in the first place rather than his win per se, but that he held it together for the full three weeks was pretty surprising in and of itself. While Thomas has a few good one week races, Carapaz has a couple himself, plus some podiums in decent ones - and there are people out there like Špilak, Izagirre and Luísle who are good over one week but don't have the endurance for three. Oh, and Richie Porte, who took how many years to finally actually beat his debut GT result?
Carapaz has had a thread of people talking up his potential since before he even made it to Europe. He won the Vuelta a Colombia for espoirs, and when he came to Europe with Abarcá, Los Frailes put him in the amateur team because of their concern following the Argiro Ospina saga, rather than because they didn't trust him, and he adapted quickly, laid waste to the Spanish amateur scene and did well as a stagiare, being at least reasonably competitive in some decent Italian semiclassics. He was 2nd in the Route du Sud as a neo-pro, and was also 14th to La Pandera and 11th to Angliru in his first Vuelta, to finish 36th overall. Carapaz podiumed Coppi e Bartali and won the Vuelta a Asturias in the warmup to last year's Giro, and won the latter again this year too. He was top 20 while working as a domestique in the Vuelta as well as his 4th in the Giro.
And while Carapaz came to this Giro as effectively a wildcard second-in-command for Landa, Thomas kind of came to that Tour in a similar position; he had been groomed to be replacement leader should Froome not ride, but Froome did ride. And let's also consider the method of winning. Carapaz lost time in the TTs and gained it in the mountains. Thomas, by skillset, you would expect, would have done it the other way round. But he didn't, he won back to back mountaintops, the first time at the Tour since Lance.
But let's also be fair: he has to actually successfully win it first.