The WAN is evolving and SD-WAN is all the rage. It promises to remove the constraints of legacy connectivity technologies, namely MPLS, and create a flexible, resilient, and secure network.
MPLS is a privately managed backbone with built-in Quality of Service (QoS). MPLS services deliver predictability — whatever contention exists for its backbone is managed by the MPLS provider.
Packet loss and latency statistics are more consistent and much lower than those of the public Internet. And to back up that point, MPLS services come with guarantees of availability (99.99% per year uptime), packet loss (.1% is typical), and latency on a route-by-route basis.
Just as important, MPLS services are mature services built for the enterprise. Aside from the SLAs, they come with integrated invoicing, end-to-end delivery, and management.