Kittel has always been an ITT specialist (3rd and 4th at the last two ITT Worlds U23, and always putting in good ITT showings) - and because of these big ITT performances we have perhaps overlooked him as a sprint prospect; good results in the early season has led to confidence and team support (long time sprinter Kenny van Hummel has been let go, and Skil have reinforced the train for Kittel).
Here's Kittel as a young prospect:
1st, Memorial Davide Fardelli ITT 2008
1 stage, Tour du Haut-Anjou 2009 (from 4 man breakaway)
2nd, Flèche du Sud Prologue ITT 2009
2 stages, Flèche du Sud 2009 (from sprints)
4th, Neuseen Rund um die Braunkohle (not a junior event! Beaten by Greipel, Haussler & Siedler; beat the likes of Ciolek and Hondo) 2009
1 stage (from solo attack) & 1 2nd (in a sprint, behind Stauff), Thüringenrundfahrt 2009
1st, Euro Championships ITT U23 2009
4th, World Championships ITT U23 2009
3rd (ITT), 5th & 2nd (sprints), Mainfrankentour 2010 (2nd overall)
3rd, Festningsrittet 2010 (including a stage win in the uphill finish of the queen stage)
3rd, Memorial Davide Fardelli ITT 2010
3rd, World Championships ITT U23 2010
It actually looks like as he's progressed he's been less of a pure ITT man and become more focused on his sprint. As he's now got a proper team around him for that (remember, he was on Thüringer Energie Team as a Junior, where Degenkolb matured as a sprinter faster than him, so Degenkolb was usually leader while Kittel would lead out or focus on ITTs, therefore he may not have produced the results you may expect in the sprints).