It's hard to believe a 6-4, 205-pound receiver who runs a 4.38 40-yard dash and boasts a 39.5-inch vertical jump can sneak up on someone, but that is exactly what Tyrell Williams did last season.

The Western Oregon product emerged from relative obscurity last year to make the Chargers as an undrafted rookie free agent.  Although he saw limited action, he ended 2015 with a bang, speeding away from the eventual Super Bowl Champion Denver Broncos for an 80-yard touchdown in Week 17.

While he may have surprised people last year, Williams is no longer flying under the radar.  In fact, Philip Rivers offered rave reviews for how the 24-year old performed during his second career offseason program.

"He's one of those guys that you saw flashes of (last year that) this guy could be something," he said.  "You saw all those flashes. Not comparing the exact styles or anything, but he reminded me (of) Malcom (Floyd) when Malcom got here and we came here together of 'Gosh, was that Tyrell again?!' (It was) once in a while throughout camp, and then there he is again.  Gosh, he played at a small school but if he could come along, he could have a chance.  And I think he would even tell you that he's still coming along.  But it does look like he's going to have a chance to make the team and help us.  We'll see as he continues to progress, but he's come a long way since last year."

Williams always had the speed and height to make plays based on his God-given ability.  However, Rivers believes the wideout has taken his game to a whole new level based on his work ethic.  There is one area in particular where Williams has improved over 2015.

"Just in general route running," Rivers said.  "When a guy is that big and fast, you know he's going to be able to run straight and run by you.  And he's probably going to be able to do all of those things vertical without a lot of change of direction.  So I think his biggest thing is learning how to run routes. Learning how to run all the routes and getting in and out of breaks as a longer guy.  That's where I think he's (really improved). Last year he came along some over the season, but I think this year with (Wide Receivers Coach Nick) Sirianni wearing him out, he's really improved."

As Rivers noted, his QB coach last year is now in charge of the team's wide receivers.  He too has been impressed by number 16 and his unique skillset.

"Tyrell is very eager to learn, and he's very eager to improve his game," Sirianni said.  "He's hungry.  He takes every little thing you give him, and I have seen him steadily get better every single game.  He's taken the opportunities he's gotten, and he's proven to me he has the abilities you need to beat press man coverage.  He catches the ball well, and he's big and fast. He's relentless and he can run all day.  When a player can do that, he wears a cornerback down.  His arrow and game are ascending quickly."

General Manager Tom Telesco is another member of the front office who recently praised the young wide receiver.

"Tyrell is one of our players who has made the biggest jump this off-season," he said in his latest live chat. "He has competed very well vs our DBs and (we) expect to see further growth in training camp."