There's no doubt that Frank Gore is slowing down. His Rushing NEP per rush sits at a miserable -0.11, which paces him for the worst season of his entire career.
He's scored a grand total of 5.8 PPR fantasy points over his last two games combined. One of those contests was against St. Louis - his opponent this weekend - a team that ranks 11th against the run this season. If you want to beat St. Louis, you have to attack their bottom-tiered secondary. And if you end up playing Frank Gore, you're mostly banking on a touchdown.