One word can sum up the most common strategy for network defense "boxy." Building and maintaining a strong perimeter has a long and storied history. Consider a castle with its moat, high walls and drawbridge. That is how most networks are defended. In a box. Currently, the mentality is: "Do you want to protect a new system?" Put it inside the box. "Processing personal information?" Put it inside the box.
While the "box" approach was successful in the past, it's an antiquated model. And, while the conventional approach has been occupied with defending the castle from a ground attack, adversaries have deployed an air assault with the latest modern weapons.

User's Choice
Over the past decade, there has been a quiet revolution with how IT systems and services are used within organizations. Fed up with a lack of options, viable solutions and a general disconnect with the business, users have taken matters into their own hands.
This evolution started with the rise in mobile usage. Early on, traditional security teams focused efforts on stopping mobile usage. Eventually, they acquiesced and accepted mobile devices, but only those that were "approved." Ultimately, reason triumphed and mobile is now treated in a more logical fashion. While still four letters, "BYOD" is no longer a bad word. Unfortunately, we are now seeing the same cycle with cloud services.

Consumer is the new Business
Consumer-focused services are making significant inroads into enterprises around the world. It is fairly common to see large volumes of outbound network traffic utilizing services such as Dropbox, Google Apps, Github or any number of other cloud-based applications. In fact, these services have begun to incorporate features and functionality specifically targeted to the size and scope of various business operations.
Think of this as a "bottom-up" approach. It is a sign that users in organizations are pushing technology adoption just as much if not more than a traditional "top-down" approach. Overall, this should be seen as a positive. The shift is now aligning IT with the actual focus of the organization. It is a move toward technology that works in the "real world," instead of simply looking good "on paper." However, it's not all unicorns and rainbows.