The Braves announced Heyward had two plates inserted in his jaw during a surgical procedure performed by Dr. Glen Maron on Thursday morning in Atlanta.
This is a big blow for the Braves, who have gained their 15 1/2-game lead in the National League East with the help of Heyward, who has batted .345 with a .408 on-base percentage and a .586 slugging percentage since moving into the leadoff role on July 28. Atlanta has averaged 5.04 runs per game while going 19-4 during this span.
Heyward already missed nearly a full month early this season after undergoing an emergency appendectomy in Denver on April 22. He returned on May 17 and struggled for a few weeks. But the 24-year-old outfielder has batted .301 with a .881 OPS in the 64 games he has played dating back to June 2.
Along with his production at the plate over the past few months, Heyward also compiled strong credentials in his bid to win a second consecutive Gold Glove Award. His 24.2 UZR/150 ranks first among NL right fielders who have compiled at least 650 innings at the position this season.
"We've faced a lot of adversity injury-wise all year long, and the guys have picked it up each time," Braves general manager Frank Wren said. "We just have to do it again."
While Heyward is out, the Braves will likely move Justin Upton from left to right field. Evan Gattis and Joey Terdoslavich could share time in left field. Over the past two weeks, manager Fredi Gonzalez has platooned Jordan Schafer and B.J. Upton in center field. Both Schafer or B.J. Upton could also be candidates to log time in left field.
When the Braves left New York to travel to St. Louis early Wednesday evening, they were holding out hope Heyward would receive better news. But there was definite concern given what they had witnessed.
With two outs in the sixth inning, Niese's pitch appeared to hit the ear flap of Heyward's helmet. Heyward immediately fell to the ground, while head trainer Jeff Porter and Gonzalez ran out to attend to him.
"It was tough. I wanted to elevate a fastball right there, and then it didn't really slip out of my hands, but it kind of just ran in on him," Niese said. "Obviously no intent, but I just felt bad. It's every pitcher and every hitter's worst nightmare. I just hope he's OK."
After a few minutes, Heyward stood up and walked off the field with Porter holding his arm. Schafer pinch-ran for Heyward, who was spitting blood as he went toward the dugout.
"He never lost consciousness," Gonzalez said. "He was talking the whole time when he got hit with the ball. Before they took him to the hospital, he popped his head into the dugout and said 'bye' to some of the guys. I got a chance to talk to him briefly after that."