Hayne didn't follow the plan.
Chryst said Hayne got too excited.
"He didn't even get back to the line of scrimmage and he was breaking out," Chryst smiled on Thursday while recalling the play.
"He was so excited to be playing."
The story gives insight into the dilemma and growing pains the 49ers have endured with the Australian during his first season in the NFL.
The 188cm tall, 100kg former Parramatta Eel, NSW and Australian backline ace has the physique, athletic talent, a mountain of potential and a desire to work and learn how to play in the NFL.
The problem is despite his age of 27, right now he's a rookie with relatively little American football experience who, as was shown on two key plays against the Lions, makes crucial mistakes.
"We got a little bit frustrated with him," Chryst admitted.
Hayne understands that, but after almost two months on the 49ers' practice squad he relished the chance to play the Lions.
"I guess over time I'm going to get better," Hayne, who says he can't wait to fly back to Sydney, spend time with friends and family, swim in the surf and drink plenty of coffee, said.
"I'm excited for my future because I'm still learning and still developing."
Hayne is expected to play running back on Sunday (Monday 8.30am AEDT) in the 49ers' final game of the season against the St Louis Rams.
The fact he's on the 53-man roster for the final game gives the 49ers the Australian's rights for next year.
If he was still on the practice squad other teams could pursue him.
Ironically, when Hayne returns to the 49ers' headquarters in Santa Clara next April there is a good chance the team management and coaches he spent the past year with could be gone.
With the 49ers' 11-loss, four-win record, Hayne's future in the NFL is probably more secure than general manager Trent Baalke, coach Jim Tomsula, Chryst and special teams co-ordinator Thomas McGaughey with calls for all four to be fired.
Chryst, on the hot seat because the 49ers have the worst offence in the NFL, appears to be a fan of Hayne.
His face lights up and a smile breaks out when he talks about the Australian.
It's not the case with Tomsula or McGaughey, with both appearing uncomfortable talking about him.
McGaughey, when asked on Wednesday about Hayne possibly returning to his special teams unit as a punt returner - the position most experts say is ideal for Hayne's talents - quickly said he would be sticking with Bruce Ellington.
Chryst said it's still hard to define Hayne as a particular player or compare him to any other NFL player.
He spoke about how Hayne was an elite athlete who craves to get the football in his hands and has a "swivel hip" running style that makes tacklers miss.
Chryst also cringed as he described how Hayne still runs with his pads too upright.
"You're a little bit worried he's going to get his block knocked off going so high through the line of scrimmage, but he's kind of got a knack for that," Chryst said.
While McGaughey doesn't seem to be keen to have Hayne back on special teams, Chryst envisages that is where the Australian's talent could best be used.
But, not just offensively.
Hayne could be used in a defensive role in kick offs or punts, using his big, fast body and tackling ability from his years in the NRL.
"I think he'll become a really dynamic special teams player on both sides of the ball," Chryst said.
"I think he can run, I think he's big, I think he is hard to block, I think as he works on fielding punts he's going to be a really exciting player to watch moving forward and we really like him."
-AAP
