Since my stage racing career consists of one weekend near Camp David in 2002 (the old Giro di Coppi), I'm not speaking from much experience, but it seems logical that riders and teams would want to break up a three week race into segments and form an approach for each portion. And we fans, taking our cues from the riders, would follow suit.
For Le Tour, this is easy to do. Like clockwork, the Tour parcours generally consists of a first week of sprint stages, a rest day, then a second-week run through the Pyrenees or Alps, then another rest, and finally a third-week swing through whichever mountain range wasn't covered already before zipping up to Paris. Weeks 2 and 3 will each include a significant time trial. The only variables include moving the main challenges up or back a couple days, depending on whether you want some sprint stages toward the end, but the gist is the same. Rinse, lather, repeat.
Consequently, every GC rider is in survival mode the first week, while looking to peak between stages 10-20. Everyone on the planet, fans and riders alike, knows which stages will settle the Tour, and while the races themselves are exciting, the predictable progression often leaves us watching day after day knowing nothing is going to happen.
Not so at the Giro. Since the entire country is one mountain range after another, there are usually challenges sprinkled throughout the race... even if the biggest are usually saved for the end. Last year Ivan Basso took a quick chunk out of his rivals on stage 8's climb to Passo Lanciano, a course similar to Montevergine. Savoldelli lost 2.20 and was already done. Simoni lost 1.15, while Cunego, already hurting from the team time trial, limited the damage to 0.30.
2005 was more like a Tour course (though even then week 1 featured plenty of short, dangerous climbs), while in 2004 Simoni and his trusty lieutenant Cunego put the wood to the peloton on stage 3 with an escape on the Corno Alle Scale, a 12km jaunt at more than 6% average. The race was hardly over, but by stage 7's climb of Montevergine the pecking order had been established. In 2003, similar gaps opened up on the Terminillo, on stage 7... and so on.
Maybe the riders still think of the Giro d'Italia as a typically back-loaded Grand Tour, since the worst of the Alps and Dolomites nearly always come at the end. But while you can't win the Giro in week one, you can certainly lose it by not bringing your climbing legs to the initial start. And as DiLuca seems intent on proving, you can send some early messages to your rivals, fans and sponsors... all good things. Whether or not the riders appreciate these early tests, the fans are the big winners, because as we saw yesterday, the fun starts on day one at the Giro and never lets up for long.