The emergence of Danario Alexander has been one of the most fascinating subplots of the fantasy season.

Alexander, who has had more knee surgeries over the past 5-6 years than most people have teeth cleanings, signed with the Chargers on Oct. 18. He has played in seven games with San Diego, but you can throw out the first of those games, in which he made only a token appearance. In the other six games, Alexander has produced 555 receiving yards and five TD catches. Project that over a full season, and we’re looking at A.J. Green-type numbers. Plucked off the scrap heap, Alexander has been a true impact player over the second half of the fantasy season.

Perhaps Alexander’s recent exploits aren’t all that shocking to you if you remember his final season at the University of Missouri. As a senior in 2009, he had 113 receptions for 1,781 yards and 14 TDs, forming a lethal pitch-and-catch combo with (wait for it …) Blaine Gabbert. So how did Alexander go undrafted by NFL teams the following spring? Because he had already undergone multiple knee surgeries in college and then sustained another knee injury at the Senior Bowl. Not even Dr. Nick of “The Simpsons” would have given him medical clearance in the spring of 2010.

For the moment, Alexander’s knee seems to be sound (knock wood or knock cartilage — whichever you prefer), and he’s fulfilling his vast potential. What’s also pretty cool is that Alexander has helped perk up Chargers QB Philip Rivers, who didn’t look especially perky early in the season. In San Diego’s first seven games, Rivers averaged 235.1 passing yards and 1.4 TD passes. In the six games since Alexander started catching passes for the Chargers, Rivers has averaged 253.8 passing yards and 1.8 TD passes.