A hint of a smile crept across Vance Joseph's face, a longtime NFL defensive mind offering the highest possible kudos to the threat at quarterback the Broncos will face in Los Angeles on Sunday.

Everything, in simple terms, is working for Chargers quarterback Justin Herbert right now. There's the arm: third-highest quarterback rating in the league through two weeks on intermediate throws. There's the processing: most passing yards in the NFL on play-action throws. And there's the sneaky legs: 63 yards on 16 carries thus far.

"He's a special athlete," Broncos defensive coordinator Joseph said Thursday. "He's playing at a high level right now. He's probably the MVP right now, after two games."

The Broncos defensive coordinator had a heap of praise for Herbert and Jim Harbaugh's offense in Los Angeles, as Denver's defense tries to collect itself for a key divisional matchup after being knocked around by the Colts last week. Indianapolis confused the Broncos with rookie Swiss Army Knife Tyler Warren last week, and the Broncos "mismanaged a couple zones" against swings to Indianapolis running back Jonathan Taylor, Joseph admitted Thursday.

Denver can't afford the same mistakes Sunday against Herbert and the Chargers, who've crafted a dynamic play-action game off heavy-personnel looks that Joseph affirmed was unique in the NFL. Harbaugh's teams, naturally, are run-first. But suddenly, the Chargers are firing on all cylinders in leveraging the ground game to open up opposing secondaries, as Herbert has thrown for 560 yards and five touchdowns with no picks in two games.

Herbert is also using the threat of his legs as effectively as he's ever done in a six-year NFL career.

"He's escaping on major downs -- second-and-long and third down -- to keep drives alive," Joseph said. "So, how we rush this guy is going to be key."

Greenlaw and Engram out again: There's no present light at the end of the tunnel for Broncos ILB Dre Greenlaw, who was again working on a side field and inactive for Thursday's practice for a second day in a row. Greenlaw is now doubtful to suit up for Sunday's matchup with the Chargers, leaving next week's game against the Bengals as the last possible chance to validate Denver for not placing the veteran linebacker on IR at the start of the year.

Tight end Evan Engram's status is in question, too, after missing another day of practice with a back injury.

Good injury news: Denver, at least, may not be down two linebackers in Los Angeles. Backup Justin Strnad was a limited participant Thursday after missing Wednesday's practice with a foot injury. Safety Talanoa Hufanga (chest) was also a full participant after being limited Wednesday.

Joseph backs up the DPOY: Yes, Broncos cornerback Pat Surtain had one of the most active days of his NFL career Sunday. Yes, the Colts beat him on a few routes. Yes, Surtain admitted Wednesday his technique was slightly "lazy" in footwork and positioning.

But Denver's defense is trying to actively force the ball in Surtain's direction sometimes, Joseph said Thursday. He had to make more plays. But Joseph isn't worried about the two-time All-Pro.

"I will welcome teams attacking Pat every week," Joseph said.

Broncos DC Vance Joseph on Chargers QB Justin Herbert: 'Probably the MVP right now'