RENTON, Wash. -- As if he doesn't already stand out with a 6-foot-4, 229-pound frame that's so muscle-bound it looks like a human Batsuit, DK Metcalf's on-field look includes an accessory that's impossible to miss: a mouthpiece inspired by a pacifier.

Metcalf knows the owner of the football equipment and apparel company that makes the mouthpieces -- Battle Sports Science -- and requested a few of them in different colors before the season.

"Just me trying to be creative and bringing out my personality with the mouthpiece," Metcalf said.

But why a pacifier, of all things?

"I'm a baby in the league," he said. "I'm a rookie, so I'm young, but I try to play like a grown man."

Metcalf has done that in more ways than one. He has been the type of big wide receiver who for years has been coach Pete Carroll's great white whale. And Metcalf has produced more than expected for a rookie who appeared in 21 games in college -- in a spread offense, no less -- and plays a position that typically comes with one of the NFL's steepest learning curves.

Just look at the numbers of the eight rookie receivers who were drafted before the Seattle Seahawks traded up to take Metcalf with the final pick of the second round. Only one of them -- Metcalf's Ole Miss teammate, A.J. Brown -- has more than 25 catches and 400 yards.

Meanwhile, Metcalf leads all of them with 29 catches, 525 yards and five touchdowns. Through nine games, those numbers put him on pace to be the most productive rookie receiver the Seahawks have had under Carroll, topping Doug Baldwin in 2011 and Tyler Lockett in 2015 in all three categories.

Metcalf's 18.1-yards-per-catch average is eighth among NFL wide receivers and second among rookies. The least impressive measure of his rookie season: Metcalf has converted 54.7% of his targets into receptions (29 of 53), which ranks 71st among all wide receivers.

Then again, there's a reason quarterback Russell Wilson has thrown to Metcalf more than anyone aside from Lockett. And it's not his mouthguard.

"He's been great all year," Wilson said. "When he came in, he was really prepared. I think he had a chip on his shoulder and just ready to roll. He's everything that you want him to be: high character, extremely amazing work ethic, obviously a ballplayer, a guy that can make great plays. He has a relentless approach to the game when he's playing and also when he's practicing and studying film."

And Metcalf has been a better route runner than his toughest critics would have predicted. That was the knock on Metcalf coming out of college and a reason he fell to No. 64 after being a first-round fixture in most mock drafts.

Offensive coordinator Brian Schottenheimer said it's the area where Metcalf has grown the most. He repeatedly pointed to a slant-and-go -- or sluggo -- route Metcalf ran during his two-touchdown performance two weeks ago in Atlanta. It resulted in an incompletion when Metcalf couldn’t hang on to a floating pass from Wilson while falling out of bounds, but Schottenheimer was impressed with the way he manipulated the defensive back off the line of scrimmage to gain leverage, calling that "an intricate thing that usually young players don't do."

"When we first got him, again, you come out of the offense at Ole Miss and you're wondering what exactly he can run, what he can do," Schottenheimer said. "There's not a route that we're really not comfortable with him running. That allows us to move him around and put him at different spots."

Metcalf followed up his two touchdowns against the Falcons with six catches for 123 yards (both career highs) and another score last week against Tampa Bay. Carroll was impressed with the awareness Metcalf showed in the final minute of regulation when he raced to the sideline to stop the clock after both receptions. When the game went to overtime, Metcalf drew an illegal contact penalty, then hauled in a 29-yard reception to set up the winning score. He made the catch while falling to the ground despite cornerback Jamel Dean grabbing his face mask.

It turned Metcalf's head and sent his mouthpiece flying right before the ball arrived.

"He just continues to do things really well," Carroll said. "People who doubted that he would be a good football player might wonder is that just lucky or whatever. He's got the presence of mind. He's a real competitor. He's the real deal. We've been around enough young guys, we know what they're like when they come through the process. He's not typical. He's atypical. He's well ahead of the curve in his smarts and awareness and savvy."