So much for that.
This week, Jacobs snapped at fans who criticized him for posting pictures on Instagram of when he played with the New York Giants.
"I am on this team rotting away so why would I wanna put any pics up of anything that say niners," Jacobs wrote on Instagram, according to Comcast SportsNet Bay Area. "This is by far the worst year I ever had, I'll tell you like I told plenty others."
Jacobs' displeasure has been bubbling just beneath the surface since he finally got healthy, after sustaining an knee injury during the preseason.
Actually, "beneath the surface" might be a stretch -- everyone knows Jacobs isn't happy. He made his 49ers debut two games ago and has just five carries in two games this season.
"I don't understand why people are angry at me because I wanna do what I am paid to do," Jacobs wrote on Twitter. "I am a competitive person, I think people should be mad if I didn't wanna play, but I forgot the people that's pissed they don't have a athletic bone and their body. As for all of my Instaram photos I don't have any niner pics, if you'll find me some pics I'll put them up."
An opportunity opened up in the 49ers' backfield when running back Kendall Hunter was lost for the season, but there's no guarantee Jacobs will be chosen to complement Frank Gore. CSN Bay Area reported rookie LaMichael James is expected to be active Sunday for the first time this season when the 49ers host the Miami Dolphins, and Anthony Dixon has been up for every game with special-teams duty.
Jacobs might have to wait longer for that picture.
UPDATE: As expected, Jacobs was not in Harbaugh's plans. Jacobs is inactive for Sunday's game, but James will suit up as Gore's backup.
Follow Kareem Copeland on Twitter @kareemcopeland.