It was a Pro Bowl season for Jared Cook. The first of his career at the age of 31. This was his second straight season leading the Raiders in receiving and he hit career highs in catches (68), receiving yards (896), and touchdowns (6). Jon Gruden likes tight ends, and Cook thrived.
You need more evidence Gruden likes tight ends, Lee Smith and Jared Cook both started every game which means the Raiders lined up in two-tight end sets to lead out every game. Smith may not catch a lot of passes, but he is a beast as a blocker.