"You've got to keep your thumb on that cat," running backs coach Kirby Wilson said of his ultra-quick rookie runner.
The Steelers aren't shy about their motivational approach to Rainey. It began last spring when Wilson was asked by reporters about whom he was going to – let's keep it clean here – mess with at that day's practice.
"Oh, that's easy," Wilson said. "Number 22."
And of course Wilson, with the help of coach Mike Tomlin, rode Rainey hard that day and every day last spring.
When asked about it, Maurkice Pouncey, who grew up in the same house with Rainey, said, "Good. He probably needs it. Heck yeah." Pouncey saw it as a good sign.
"Oh, they love him. They really, really love him," Pouncey said of the coaching staff. "I hope it stays that way. I hope he stays here with me as long as he can."
Well, if sharp needling means love, the coaches apparently still carry those feelings about Rainey. Just the other day, at the start of the first full-contact practice of the season, the horn blew, players began running to their individual stations, and Tomlin shouted, "OK, 22, time to die!"
Of course, that's the text message Rainey, number 22, had sent to a girlfriend to break up with her in college. It led to criminal charges – and a year's worth of verbal abuse from Tomlin and the rest of the Steelers.
"I hear it every day, about five times a day," Rainey said as he smiled and shook his head. "It's all good. I made a bad mistake in the past but I moved on. It's funny now. I'm glad I'm here."
Rainey is a good-natured rookie whose upbringing couldn't have been worse. He was born in jail, raised by his grandmother, moved back with his mother at 14 after she was released from prison, and then left her two years later because "we didn't get along." Then he moved in with the Pounceys.
"It definitely helped me in the long run," Rainey said. "I definitely became a man at a real early age. But football definitely helped at the same time."
Rainey meshed easily with the Pouncey twins on the football field. Maurkice said Rainey ran behind him and Mike about 80 percent of the time on their way to three state championships in Florida.
And how did it go inside the Pouncey household?
"Oh, they loved me," Rainey said, "because I have a good personality, good smile, good kid, everything. Who can't love me here?"
They do love him in Pittsburgh, in spite of the constant needling and in spite of a flair that had Rainey as the only player on the field Saturday dressed in his gold football pants, a "Rainman" embroidered belt towel, and his rainbow-tinted visor.
"The defense is clumsy," Rainey explained. "People get hurt from defense because they're so clumsy. You never know what happens, so I always put on full pads."
Clumsy defenders are one thing, but full pads didn't help Rainey that day against "Big Bertha." The gigantic tackling dummy that hangs from four iron poles was first on the list of challenges for Rainey during that first day of contact.
"Everybody started walking toward some big tackling dummy and I was like "What is that?!" Rainey said. "I've never seen that in my life. That thing is big. I'm ready for it next time"
He wasn't ready this time. The bag sent Rainey flying and he banged his helmet off one of the iron posts. The coaching staff then sent the 178-pounder off to work with the receivers as the backs went into their sled and blitz-pickup drills.
"Coach Tomlin made the decision yesterday just to hold off on it," Wilson said of Rainey's excused absences. "We've got some things we're going to give him that he can draw from when it comes time to pass-protect in a game. But we didn't want a situation where he was going to be bull-rushed and they were going to win every time, so we just decided to continue to work with him and give him some other ways to protect when it's real football."
It's not as if the defensive players respect Rainey any less because of his size, rookie status, and flamboyancy.
"It's going to be interesting guarding him one-on-one in pass drills," said Larry Foote. "He looks like he's going to be a weapon out the backfield. He's electrifying."
"He's very explosive," said Lawrence Timmons. "He's a game-changer in the way he can score a touchdown any given time."
"We give him a hard time, but we really like him," said Brett Keisel. "He's so quick. He's bound to help us."
"He's well-liked in our locker room, and specifically in the running back room because he's smart," said Wilson. "And what I mean by that is he's football smart and he's respectful to players who have been here. So that's why they've accepted him, and they know he's a guy who's going to work hard and he's got some skills that can possibly help us. So they've accepted him. As long as he continues to work hard, be respectful, keep a smile on his face, they'll continue to allow certain things. But they're teaching him.
"The key," Wilson added, "will be what's going to happen when he really gets his rear end knocked off. What's going to happen next? Will it affect him mentally? We'll find out. Those are things you've got to find out in camp. You know it's coming. It'll happen in one of these drills where he's going to get his rear end knocked off. Hopefully he'll do what we think he'll do: Get back up, shake it off, and go again."
And maybe then it'll be time for Rainey to live.