He never had a 100 yard game against the Seahawks, so far.
He's had 10 games (of 15) with 100+ yards from scrimmage and 8 TDs in 15 contests vs. the Seahawks. He also averages ~13 fpg against the 'Hawks in standard leagues and over 17 fpg in PPR leagues. Remember, with SJax you get yards on the ground and through the air, one of the best pass catching RBs (if not the best) of the past decade. Still, he's a flex option at best this week.