Someone will soon be knocking on Frank Gore's door, that someone is Father Time. Frank Gore has been a dominant running back in the NFL for nine years, and still continues to be, most NFL fans expected him to be on a decline this season, yet he has showed no sign of slowing down, yet it is right around the corner.
Experience (Not the good type of experience):
Frank Gore has experience, and it isn't the experience that's going to benefit him, this experience is only going to cause detriments in his running ability.
Gore has been in the NFL for nine years, most running backs are lucky to last even four to five years in the NFL(at a high level), that is nine years' worth of punishment on his body, and this is another reason Gore will soon be on the decline; sure, Gore can last even four more years in the NFL, but not a high level, he's 30-years old and he will enter his decline sooner than later.
San Francisco 49ers' Offense:
San Francisco's offense is a run-first offense, if they are unable to successfully run the ball, they will not be successful; the 49ers want to ensure their success so they are going to pound the ball against opposing defenses, resulting in Gore accumulating 18.25 carries per game, Frank Gore or not, a 30-year old running back isn't going to last much longer in a team that has established itself as a run-first offense.
Punishment on legs:
The younger Frank Gore played in a professional football league where defenders could aim for the upper-body without getting heavily fined. With the strict regulations on tackles on the upper-body, defenders are now aiming for the lower body, mostly targeting the knees of ball carriers, and this doesn't help the 30-year old Gore's case. A defender will definitely aim lower on Gore because of his bruising run-style and his tendency to lower his helmet when contact is going to be made, this will result in him taking more punishment on his legs, which will prove to be a detriment as he hopes to elongate his career in the NFL.
This goes hand-in-hand with experience, not only has Gore taken nine years' worth of punishment, he is 30-years old, which isn't young for a running back in the NFL. In most cases, a 30-year old cannot do what a 22-year old can do, the speed and agility just isn't there anymore; it hasn't completely diminished from Gore, but it will soon, and the 49ers' organization knows this, this is why they have drafted Marcus Lattimore in the 2013 NFL Draft to eventually receive the majority of the carries when Gore enters his decline.