Raiders lose OT Watson to torn Achilles tendon

August 14, 2015; Oakland, CA, USA; Oakland Raiders tackle Menelik Watson (71) on the sideline during the fourth quarter in a preseason NFL football game against the St. Louis Rams at O.co Coliseum. The Raiders defeated the Rams 18-3. Mandatory Credit: Kyle Terada-USA TODAY Sports

Menelik Watson will have to wait another year to prove he's starting material.

The Raiders tackle suffered a ruptured Achilles against the Cardinals on Sunday night. He'll miss the entire 2015 campaign.

"That's a tough break for us," head coach Jack Del Rio told reporters. "It's really unfortunate. He was having a great camp for us."

The former second-round pick was impressive this summer, according to Del Rio. He needed another year of reps to combat his relative inexperience -- 17 games played with 12 starts.

https://twitter.com/MenelikWatson/status/638190995427889152?ref_src=twsrc%5Etfw

(h/t ESPN)