OK, that may be a bit of an exaggeration.
But the first-round draft pick was so quiet his first year with the Steelers that coach Mike Tomlin jokingly called DeCastro "Mr. Personality."
DeCastro hasn't fundamentally changed but he now seems as comfortable off the field as he is on it, where the Stanford product has emerged as a Pro Bowl-caliber guard and the top escort for running back Le'Veon Bell.
"Even now if he doesn't know a bunch of people in the room he'll still be quiet," said left guard Ramon Foster, one of the more outgoing players on the Steelers. "He's a sociable guy though. Dave's just Dave and he's a character in our room. It's not like he's out here like Lurch."
He is anything but stiff, a hallmark of the aforementioned "Addams Family" character, when the 6-5, 316-pounder is leading one of the Steelers' favorite plays.
DeCastro pulls left on the counter that the Steelers run frequently with a tight end also leading the way for Bell. The AFC's leading rusher has gobbled up yardage on the play and his face lit up when asked what it is like running behind DeCastro, who simply wipes out defenders for one of the most patient backs in the NFL.
"A lot of teams can't really run the counter like we run it because we've got guys who can run and get on the edge," said Bell, who has rushed for 1,278 yards and is averaging 4.9 yards per carry. "Having [DeCastro] in front of me makes me all the more comfortable. Something that's really undervalued from linemen is their mobility and the way they can move and he's one of the best at that. He and [center Maurkice] Pouncey can run with the best of them."
That Bell gets so much credit for running with the best of them in his second NFL season suits DeCastro's understated personality just fine. But there is no question that DeCastro is coming into his own in his third NFL season.
"Football's a weird thing. You can be playing well and then you get humbled real quick," DeCastro said. "You're always chasing perfection but I feel very comfortable with where I'm at."
The Steelers do too, especially since DeCastro could go on a Pro Bowl run like former Steelers guard Alan Faneca, who made seven of them in 10 seasons in Pittsburgh.
The Pro Bowls teams will be unveiled Tuesday night and Pouncey and DeCastro are both strong candidates to earn spots in the annual all-star game.
"It's kind of like a cherry on top but there's a whole lot more that you should be worried about," DeCastro said of the possibility of making his first Pro Bowl. "You don't want to be playing football games and worrying about the Pro Bowl right now."