You can't compare 45 minute climbs to 15 minute climbs. Contador's 20 minute Verbier climb works out to the same values as Horner. This climbing performance definitely makes Horner suspect in the 3rd week of racing. It puts him on par with Froome, Contador, along with all the caught dopers. The same goes for Nibali, Valverde, and Rodriquez. Roche is looking more and more like a doper.
Someone commented earlier about endurance suffering as you get older, that is incorrect, endurance doesn't suffer in fact it may increase, but peak power does decline starting in the mid 30s and the shorter climbs should favor younger riders up to 32-33 years of age at maximum. The steep punchy very short climbs like the Mur de Hoy favor riders than that because pure power wins over prolonged power on those shorter efforts. It's why a guy like Gilbert is not as dominate on those anymore as there is a very small window and why he should probably start concentrating more on 3-4 day to week long stage races to include the classics as experience helps in races such as those.
The only thing going for Horner is his ability to do work day after day which is the product of his training age. However, fatigue works against him as it is harder to recover from bigger efforts as you age and easier to recover when you are younger. The main problem is it is hard to improve your fitness over a 3 week grand tour without starting out riding like a brick anvil up the first couple of climbs at the beginning of the race. Age should lead to greater consistency and less wins against top guys in a 3 week race, while inexperience should show some variations, but more frequent stage wins in races like the Vuelta. I don't see that and the Vuelta peloton seems less clean than the Tour one, but the Vuelta also has shorter faster stages than the tour. For Horner to do this he had to come into the Vuelta with a very high level of fitness which begs the question how is this happening? Is it because he has raced less than anyone else in the race this season? Those are important questions to consider which kind of throws the whole Froome/Wiggins strategies of winning almost everything in site up to the Tour.