Perhaps it shouldn't be all that surprising that Antonio Gates -- one of the better tight ends in NFL history -- is slowing down at 36 years old. But what is surprising is the pace at which his rookie successor, Hunter Henry, is helping speed up that transition.

Henry's ascension is particularly surprising given the typically slow transition of tight ends from college to the NFL. Indeed, per Pro Football Reference, only four tight ends since 1970 have achieved more than 800 receiving yards in their rookie season.

But Henry has really looked the part in the last four games. Using our signature in-house metric, Net Expected Points (NEP), we can see why Philip Rivers is looking his way more than Gates these days. NEP allows us to quantify player performance above-or-under expectation using down-and-distance data, and historical performance in identical on-field situations. You can learn more about NEP by checking out our Denver Broncos defense.

Essentially, every time Rivers directs the ball Henry's way, the San Diego Chargers are adding a point to their expected point total. By contrast, Gates is sporting a lowly 0.35 Reception NEP per target, far lower than his career-low 0.56 Reception NEP per target he registered in 2013.

It will be a sad day for Chargers fans when Gates hangs up his cleats. But what Henry has shown so far has to have them excited for the future. Gates is now likely safe to drop from your fantasy roster.