Third in a series of positional looks courtesy of Yahoo! Sports Contributor NetworkThese days in the National Football League, there's so much emphasis placed on the performance of the quarterback that you wonder if he's the only player on the field.Of course that's not accurate. But at times, you would almost think that's the case.While today's NFL is deep when it comes to wide receivers, tight ends continue to make their mark in this pass-happy league. And the numbers these players have put up in recent seasons have been phenomenal. A total of five tight ends led their respective teams in receptions in 2013.So here's the third of many looks at the other positions on the field and their importance. A one-man show is great in tennis, bowling and handball. It doesn't work when it comes to football.Now it's time to take a look at those aforementioned tight ends. Who are the guys the quarterbacks rely on to not only be their safety valve but come up with the big play as well? Let's take a look: