Agree he is hugely talented but I do think Valverde got near best from himself. I mean he turned pro in 2002! But if you had the best sprint of any GC rival then you would ride like him too. Why bust your guts doing it the hard way when you can just stay with the best on the climbs then finish them off in the sprint. That's how he won his world title. In Grand Tours Valverde was known to fade in the third week and had a problem with altitude.Valverde is easily one of the most talented riders of the last, let's say 20 years...
Some luck, maybe yeah. But also his way of riding, he was too conservative I think, if he had risked more in big races, I think he would had a couple of big ones more.