Jacobs, a two-time Super Bowl champion, won't be expected to carry a heavy load out of the Niners' backfield, nor should he be, now that he's approaching his 30th birthday and has seen his body bear the brunt of a brutal running style.
Rather, the 6'4", 264-pounder will be asked to serve as merely one part of a three-headed monster by the bay, albeit as the most physically imposing of San Fran's ball carriers, alongside Frank Gore and Kendall Hunter.
As Matt Barrows of The Sacramento Bee surmises, Jacobs will likely be asked to serve as a hulking runner to wear down defenses on occasion, while Gore carries the bulk of the load—particularly in the short passing game—and Hunter provides the spark as a speedy scatback.
Not unlike the arrangement in which Jacobs found himself alongside Ahmad Bradshaw and Derrick Ward with Big Blue.
Jacobs' style also happens to fit perfectly into the physical, hard-nosed, run-first culture that Jim Harbaugh has established since moving up the road from Stanford to Candlestick Park. His mere presence will bolster the Niners' backfield while allowing Harbaugh to go to the well early and often.
Which is just as well, since the marginally effective Alex Smith will be back under center, and as the Niners learned last season, the less Smith has to throw, the better.
Furthermore, by adding Jacobs, the Niners are also subtracting a key component from the Giants, who edged San Francisco in the 2012 NFC Championship Game before emerging victorious from Super Bowl XLVI. Hence, the Niners' chances of taking the next step will improve, however slightly, if for no other reason than the weakening of their competition.
Of course, acquiring Jacobs hardly guarantees that the Niners will win their sixth title, and their first since 1994, right away.
But with Jacobs, San Francisco has taken yet another small, solid step in the right direction.