The league says the hit was a violation of safety-related playing rules, in which Rule 12, Section 2, Article 6 (i) states, "there shall be no unnecessary roughness. This shall include, but will not be limited to: (i) using any part of a player's helmet or facemask to butt, spear, or ram an opponent violently or unnecessarily."
On the second play of Baltimore's second drive, quarterback Joe Flacco threw a short pass to Wallace, and the receiver was quickly wrapped up and in the process of being tackled by Minnesota cornerback Xavier Rhodes. Wallace's left knee was almost touching the ground when he was hit near the head and neck area by Sendejo.
Wallace's helmet came off after contact was made. The receiver lay on the ground for several moments before heading to the sideline with trainers. He was put in the concussion protocol and later ruled out for the remainder of the game.
Ravens coach John Harbaugh declined comment when asked about the suspension.
NFL vice president of football operations Jon Runyan handed down the suspension on Monday afternoon and gave his reasoning in a letter to Sendejo.
"The violation was flagrant and warrants a suspension because it could have been avoided, was violently directed at the head and neck area and unreasonably placed both you and an opposing player at risk of serious injury," the letter read.
Coach Mike Zimmer defended Sendejo's hit during his Monday press conference under the belief that Wallace established himself as a runner.
"I think the receiver took five steps after he caught the ball and I think [Sendejo] hit him with a glancing blow," Zimmer said. "He established position as a runner, took two extra steps. Xavier was trying to pull the ball out, which he ended up doing. The guy went down a little bit, but in my opinion, [Wallace] was a runner."
Sendejo has up to three business days to appeal the suspension, per the NFL's collective bargaining agreement. Under the terms of the suspension, the safety will eligible to return to the active roster on Monday, Oct. 30, one day after Minnesota plays Cleveland in London.