Comcast speed dips then recovers rapidly after the Netflix agreement is made

What caused the sudden improvement in Comcast service and how much did it cost?

As shown here, Netflix download speed began dropping for Comcast customers last November and began picking up in February. It rose another 2% in April.

What happened? The cynical, but quite plausible, answer is that Comcast refused to upgrade their equipment while negotiating with Netflix on fees for faster service, resulting in poor performance and angry customers, and they made the necessary investment after a deal was concluded in February.

Infrastructure investment is central to the network neutrality debate. If this improvement was due to investment upstream from Comcast, they should present data demonstrating that. Regardless of who made it, I would like to know how much we are talking about here -- what did it cost to increase performance so dramatically?

The public, the FCC and the FTC need that sort of transparency to formulate policy that will incent infrastructure investment.