Reliever José Soriano's first pitch of the inning -- an 86-mph curveball -- hit the ducking Alonso near the back of the neck. Alonso briefly remained on the ground and manager Buck Showalter ran out to check on him. The Mets lead the National League, and rank second in the majors, with 84 hit by pitches.
After getting up, Alonso exchanged words with Angels catcher Logan O'Hoppe, which caused both benches to clear. Alonso was removed for a pinch-runner.
Alonso passed concussion testing. Showalter indicated that Alonso shouldn't require additional testing.
"I've watched a lot of Mets games," Los Angeles manager Phil Nevin said. "Pete's taken a lot of balls up and totally understand that. When you get upstairs a lot, anything is going to set you off a little bit."
Alonso ranks third in the majors with 39 home runs and needs one more homer for his third season with 40 or more. He has been hit 17 times, the most in the National League.
"I'm not happy about it," Showalter said. "Not happy at all."