It was the first day of hittin' season.
Yep, the pads were coming on.
"It's the first opportunity to play real football," Williams explained later. "I don't think you can get an accurate gauge of what a player can contribute until you put the pads on."
Williams hit in practice, and loved every second of it. They all hit, and the defense in particular seemed to love every second of it.
The most impressive defender -- particularly to those who've watched three months of touch football in shorts -- was Ryan Shazier, who was heard before he was seen at Sunday's practice.
"I betcha I don't miss any games," Shazier was hollering to Stephon Tuitt on the far side of the field. "Come on, let's bet I'm not going to miss any games."
And then Shazier and the rest of the linebackers moved over to the near side for the annual start of the hitting parade: backs on backers.
It's a drill in which a linebacker takes a running start at a running back stationed near an imaginary quarterback -- in this case Ben Roethlisberger, who was given a rest for the day and was standing in. The stationary back is commissioned to pick up the blitz, and it can get a tad violent.
The featured hitter the last eight years or so has been Lawrence "Law Dawg" Timmons, but Sunday Timmons appeared to pass the baton to Shazier, the 2014 first-round pick who's betting on his first completely healthy season.
Shazier was an absolute tornado in this drill on Sunday. Ask DeAngelo Williams, who whiffed on the quick-footed Shazier in their first meeting. Ask Cameron Stingily, who was trucked by Shazier later on. Or, just ask any of the backs or backers standing around the drill who gasped when Shazier laid out the 235-pound Stingily.
"Five-Oh looks like a MAN today!" shouted Mike Tomlin.
Number 50 took it over to the team scrimmage, too.
Daryl Richardson, a former running back for the St. Louis Rams who had distinguished himself in the blocking drill, took a handoff and was crushed seven yards behind the line of scrimmage by Shazier.
His brand of hitting became contagious with players such as Mike Mitchell, Shamarko Thomas, Caushaud Lyons, Montell Garner, Javon Hargrave and Tyler Matakevich, just to name a few who were dishing out some big licks throughout the workout.
It was Shazier, though, who defined the day. His crushing hit on Stingily ended the practice the way it had started it, and Steelers fans can only hope it'll be looked back upon as the day Shazier made a winning bet on a start-to-finish season.
"Hey," it was mentioned to Tomlin after the holiday had come to an end, "this Shazier fella can play a little bit."
"He should," Tomlin said with a smile. "You know, he's becoming what we expect him to become, like a lot of guys. More importantly than that he's embracing this day-to-day process. He gave us a great work day today."
As did the entire defense, and that'll be needed for any kind of run at a Super Bowl.
Tomlin, of course, wasn't about to get too excited.
"I just never try to tell a story on one performance, particularly the first one," he said. "There's going to be ebb and flow throughout this team-development process. I know you guys got stories to tell and stories to write, but that's what training camp is. Some days the defense is going to win; some days the offense is going to win. The big thing is that it's competitive and both groups are moving with an upward trajectory."
NOTES -- Fullback Roosevelt Nix and running back Brandon Johnson were "shaken up" and left practice. Tight end Xavier Grimble left with "heat exhaustion" once again. Tomlin said all three were being evaluated, but Grimble appeared to be fine after practice. ... Antonio Brown said after practice that he wouldn't hold out -- as had been hinted at by a national reporter -- but that he was hopeful the Steelers would extend his contract that still has two years remaining. The Steelers have said they would not.