During a May 29, 2017, bench-clearing incident after Giants reliever Hunter Strickland hit Morse's former Nationals teammate Bryce Harper with a fastball and Harper charged the mound, Morse (playing first base at the time) quickly interposed himself between the two players in an effort to break up the fight. Giants starting pitcher Jeff Samardzija collided with Morse while taking a run at Harper, sending both Giants to the ground and leaving Morse with a concussion. Morse was placed on the 7-day concussion list after the game. He told the "San Francisco Chronicle" weeks later that he still remembered little of the altercation and was continuing to deal with concussion symptoms, for which he was receiving daily testing and treatment at Stanford University. Harper said he was "very thankful" to Morse for stepping in, noting that he could have been seriously injured if Samardzija had gotten through and hit him. Morse missed the remainder of the 2017 season as a result of the concussion. In 2017 with the Giants he batted .194/.250/.306.