"I think getting hit by the ball is a little easier than getting hit by Shayne (Skov),Jordan 12 Cheap Real," he said, referring to Stanford's star linebacker.
Senior Anthony Wilkerson and Gaffney, who played ahead of Wilkerson two years ago, will likely receive the majority of snaps. But Ricky Seale, Kelsey Young, Remound Wright and Barry Sanders all will receive carries on what has been one of the nation's best rushing teams since Shaw and his predecessor, Jim Harbaugh, arrived in 2007.
NCAA rules allow an athlete to play professionally in one sport and maintain eligibility in another, so long as they don't receive money from endorsements. While it's rare for a player to return after missing an entire season of major college football, plenty of players have rotated between sports, including at Stanford.
When baseball season ended, Gaffney attended almost every Stanford home game and a couple on the road, including at Oregon when the Cardinal outlasted the top-ranked Ducks in overtime en route to a conference championship and the program's first Rose Bowl victory in 41 years.
The Pirates retain Gaffney's contract rights the next four years. He said the organization was surprised by his decision to leave because "they saw me trying to move up and do better. It'd be one thing if I was failing and it was like, 'Oh, he's going back to football.' They said, 'Pass a physical, and we'll welcome you back.'"
And Gaffney embodies that tough, physical style. He rarely runs out of bounds, preferring to go head-on with defenders — a mentality that often surfaced on the baseball diamond, too.
In the back of his mind, Gaffney always knew he could come back to football.
"Smiling goes a long a way," Gaffney said. "I like pressing people's buttons."
Shaw said he always knew Gaffney could come back. He just thought Gaffney would play at least two years of baseball first.
Ever since he could remember, Gaffney played more than one sport. He starred at San Diego's Cathedral Catholic High School in baseball and football and chose Stanford because of the opportunity to play both, following in the footsteps of Cardinal greats such as John Elway and John Lynch and Toby Gerhart.
Even with that scar, Gaffney said one of the reasons he jumped at the chance to play professional baseball is because football players typically don't have long careers.
Gaffney said he missed the adrenaline on football game days, the challenge of "moving another man against his will" and lining up with 10 other players as opposed to a one-on-one matchup with a pitcher. At times, he said living with a host family in State College, Pa., and being surrounded by intense Penn State football fans felt like being on another planet compared to Stanford's serene Silicon Valley campus.
Elway (Yankees) and Lynch (Marlins) played in the minors before going back to Stanford. Gerhart, the 2009 Heisman Trophy runner-up and current Minnesota Vikings running back, turned down an opportunity to play professional baseball. More recently, Seattle Seahawks quarterback Russell Wilson left North Carolina State for a summer in the Colorado Rockies' farm system before enrolling at Wisconsin for a sensational senior season.
In a perfect world, Gaffney would play both sports professionally. And as far-fetched as that might sound, pursuing that dream remains his goal.
What Shaw found out later is that Gaffney already had been plotting a return.
"I'd walk up,Allen Bailey Jersey, and I used to run the wildcat, he'd yell out, 'Tiger Gaff!' I'm in jeans and walking up there. Everyone would laugh," Gaffney said. "Little things like that, saying, 'Oh, we'll see you next year.' Coach would come up and give me his business card and say, 'Oh, we'll talk later. We'll talk later.'"
"When it's all said and done, he's going to play football for pay in the future," Shaw said.
Watching from the sideline and the stands reminded him what he had left behind.

Gaffney never charged the mound; he said he couldn't afford a fine. He learned in his first game as a professional that contact in baseball can come at a price.
Gaffney, drafted in the 24th round by the Pirates as an outfielder, batted .297 and had an impressive .483 on-base percentage for State College thanks to a style that makes advanced statisticians salivate: He drew 20 walks to 20 strikeouts and was hit by a pitch an unbelievable 20 times in 38 games.
Gaffney hasn't stepped in a baseball cage since earlier this summer and said he'll resist any impulse during football season. But he'll likely return to the sport at some point.
He wrote out the pros and cons of the decision on a whiteboard wi