"It still hasn't hit me yet," he said.
It was rewarding because the San Francisco native has only carried the ball in four games during his three seasons on campus but is on the verge of finally carving out a significant role, but even more so because of the scare he survived just last week after being in a car accident.
Yarnway was sideswiped by a driver who ran a red light, spinning his 2001 BMW into a pole. The drivers' side door was smashed in and onlookers had to help pull the redshirt junior out of his vehicle.
"My nose was bleeding, I felt like I had a concussion," said Yarnway, who was taken to a local hospital. "It was a big impact. It was a big deal.
"Football is a car crash, you know what I mean, something I'm used to. But it is definitely a blessing, in all seriousness, to have walked away from that with no injuries. It could have been a lot worse."
Despite being sore, Yarnway was able to finish the final week of practice and on Saturday showed off the role he might hold this season, catching two passes for 16 yards and carrying the ball six times working as both a tailback and fullback.
All the Golden Bear backs have seen time at fullback because of a lack of available players, but the 223-pound Yarnway has demonstrated the skill set to become a valuable contributor for the offense as a rusher, receiver and blocker. He did all three in the spring game, including converting a fourth down conversion on a fullback dive.
Head coach Jeff Tedford said Yarnway would start fall camp as a fulltime fullback.
"He made the transition," Tedford said. "Feeling his way through there and becoming a blocker is really a key."
That requires a change in mentality, unlearning everything he has been taught about playing football and has been the toughest adjustment.
"As a running back, you're like, ‘I want to go the distance right now.' But as a fullback, you have to say, ‘I'm trying to help someone go the distance,'" Yarnway said.
If the transition holds, it would give Cal a chance to get Yarnway and seniors Isi Sofele and C.J. Anderson all on the field at the same time, one at tailback, one at fullback and one at slot receiver.
"What we are trying to accomplish, it's a lot of opportunity for me to get the ball from different places," Yarnway said. "I can switch it up, go back to the dot and play tailback. It opens a lot for us as an offense."
Tedford blamed back-to-back bad snaps on a thumb injury to center Brian Schwenke.
"He probably should have had a cast, but there was no way he could snap with a cast," Tedford said. "He really played the last two weeks with a messed up thumb."
However, the Class of 2012 member was only there as a spectator, attending the spring game with his younger brother and 2013 offensive tackle Aaron Cochran.
-With redshirt junior Vincenzo D'Amato sidelined, kicker James Langford impressed by connecting on field goals of 47 and 41 yards.
The junior transfer from Cal Poly would have to sit out the upcoming season to meet NCAA requirements, but Tedford said Langford would appeal in hopes of being eligible to play immediately.
-Running back Daniel Lasco was limited by a hamstring injury, rushing six times for eight yards.
-Tight end Spencer Hagan hurt his ankle late in the fourth quarter, but Tedford did not believe the injury to be serious.
Dan Greenspan is the publisher of Cal Sports Digest and covers the Pac-12 for Fox Sports/Scout.com. Follow him on Twitter @DanGreenspan.