49ers exercise 5th-year option on Arik Armstead’s contract

In a mild surprise, the 49ers on Monday exercised the fifth-year option on the contract of defensive lineman Arik Armstead, the No. 17 draft pick in 2015 who has yet to realize his draft-day potential. Armstead, 24, has just six career sacks and has missed 18 of 32 games the past two seasons with injuries. However, he could earn $9 million in 2019 if he puts together a breakout season. The fifth-year option is guaranteed only for injury. It will become fully guaranteed if he is on the roster on Day 1 of the 2019 league year. It's a relatively low-risk move for the 49ers, who could release him without financial penalty after this season, assuming he doesn't get a severe injury.