Obi Melifonwu Placed on IR Due to Surgery on Knee Injury

Oakland Raiders safety Obi Melifonwu could miss substantial time during the regular season after undergoing knee surgery. 

Per Michael Gehlken of the Las Vegas Review-Journal, Melifonwu's procedure is "believed to have occurred last week." 

Dieter Kurtenbach of the Bay Area News Group reported the Raiders placed Melifonwu on injured reserve. 

The Raiders drafted Melifonwu in the second round of this year's draft. The former Connecticut star is expected to boost a secondary that struggled in 2016. 

Pro Football Focus' Matt Claassen ranked Oakland's secondary 17th in the NFL last season, with safety Reggie Nelson's performance drawing some of the criticism. 

"After a really poor start to the season, free-agent pickup Reggie Nelson played much better from Week 6 and on," Claassen wrote. "Still, it didn't match the level of play from either him or Charles Woodson (the player he replaced) in 2015."

With Melifonwu sidelined, the Raiders will look to second-year safety Karl Joseph to grow into his role as an anchor on defense. Joseph was Oakland's first-round pick in 2016 and appeared in 12 games as a rookie, recording six passes defensed and one interception.

The Raiders won 12 games last season due to the strength of their offense and Defensive Player of the Year Khalil Mack. If the rest of the defense can play better, with or without Melifonwu, Oakland will be a serious Super Bowl contender in the AFC.