The 49ers have placed defensive tackle Arik Armstead on injured reserve and claimed fellow D-tackle Chris Jones off waivers from the Dolphins, per Doug Kyed of NESN (Twitter links).
Armstead has suited up for all eight of the 49ers’ games this season and garnered four starts, but a shoulder injury has bothered the ex-Oregon Duck since training camp. As a result, he only took the field for four plays in the 49ers’ 41-23 loss to the Saints last Sunday. The 2015 first-round pick has amassed decent counting stats this year – 15 tackles, 2.5 sacks and a forced fumble – but Pro Football Focus ranks his overall performance a below-average 85th among 119 qualified interior D-linemen.
A third-year man, Jones totaled 24 appearances and 22 starts over his first two NFL seasons as a member of the Patriots, who cut him in April. He went on to appear in seven of the Dolphins’ games this year and participate in 19 percent of their defensive snaps before they waived him Monday.