It is difficult to provide a counterfactual here (would Obama have won if his campaign hadn't put any effort in digital?), so I am not sure if you are requiring that.
For factual analysis of the effects and strategies employed by Obama (on a casual glance, most of which support the statement that Obama's campaign was highly successful), do a search on Google Scholar. Here are a few highly cited political science sources I was able to pull (need to get back to work now).
> Digital media in the Obama campaigns of 2008 and 2012: Adaptation to the personalized political communication environment
> This essay provides a descriptive interpretation of the role of digital media in the campaigns of Barack Obama in 2008 and 2012 with a focus on two themes: personalized political communication and the commodification of digital media as tools. The essay covers campaign finance strategy, voter mobilization on the ground, innovation in social media, and data analytics, and why the Obama organizations were more innovative than those of his opponents. The essay provides a point of contrast for the other articles in this special issue, which describe sometimes quite different campaign practices in recent elections across Europe.
> From Networked Nominee to Networked Nation: Examining the Impact of Web 2.0 and Social Media on Political Participation and Civic Engagement in the 2008 Obama Campaign
> This article explores the uses of Web 2.0 and social media by the 2008 Obama presidential campaign and asks three primary questions: (1) What techniques allowed the Obama campaign to translate online activity to on-the-ground activism? (2) What sociotechnical factors enabled the Obama campaign to generate so many campaign contributions? (3) Did the Obama campaign facilitate the development of an ongoing social movement that will influence his administration and governance? Qualitative data were collected from social media tools used by the Obama ‘08 campaign (e.g., Obama ‘08 Web site, Twitter, Facebook, MySpace, e-mails, iPhone application, and the Change.gov site created by the Obama-Biden Transition Team) and public information. The authors find that the Obama ‘08 campaign created a nationwide virtual organization that motivated 3.1 million individual contributors and mobilized a grassroots movement of more than 5 million volunteers. Clearly, the Obama campaign utilized these tools to go beyond educating the public and raising money to mobilizing the ground game, enhancing political participation, and getting out the vote. The use of these tools also raised significant national security and privacy considerations. Finally, the Obama-Biden transition and administration utilized many of the same strategies in their attempt to transform political participation and civic engagement.
> The Internet's Role in Campaign 2008
> A majority of American adults went online in 2008 to keep informed about political developments and to get involved with the election.
For factual analysis of the effects and strategies employed by Obama (on a casual glance, most of which support the statement that Obama's campaign was highly successful), do a search on Google Scholar. Here are a few highly cited political science sources I was able to pull (need to get back to work now).
> Digital media in the Obama campaigns of 2008 and 2012: Adaptation to the personalized political communication environment
> This essay provides a descriptive interpretation of the role of digital media in the campaigns of Barack Obama in 2008 and 2012 with a focus on two themes: personalized political communication and the commodification of digital media as tools. The essay covers campaign finance strategy, voter mobilization on the ground, innovation in social media, and data analytics, and why the Obama organizations were more innovative than those of his opponents. The essay provides a point of contrast for the other articles in this special issue, which describe sometimes quite different campaign practices in recent elections across Europe.
> From Networked Nominee to Networked Nation: Examining the Impact of Web 2.0 and Social Media on Political Participation and Civic Engagement in the 2008 Obama Campaign
> This article explores the uses of Web 2.0 and social media by the 2008 Obama presidential campaign and asks three primary questions: (1) What techniques allowed the Obama campaign to translate online activity to on-the-ground activism? (2) What sociotechnical factors enabled the Obama campaign to generate so many campaign contributions? (3) Did the Obama campaign facilitate the development of an ongoing social movement that will influence his administration and governance? Qualitative data were collected from social media tools used by the Obama ‘08 campaign (e.g., Obama ‘08 Web site, Twitter, Facebook, MySpace, e-mails, iPhone application, and the Change.gov site created by the Obama-Biden Transition Team) and public information. The authors find that the Obama ‘08 campaign created a nationwide virtual organization that motivated 3.1 million individual contributors and mobilized a grassroots movement of more than 5 million volunteers. Clearly, the Obama campaign utilized these tools to go beyond educating the public and raising money to mobilizing the ground game, enhancing political participation, and getting out the vote. The use of these tools also raised significant national security and privacy considerations. Finally, the Obama-Biden transition and administration utilized many of the same strategies in their attempt to transform political participation and civic engagement.
> The Internet's Role in Campaign 2008
> A majority of American adults went online in 2008 to keep informed about political developments and to get involved with the election.