The 30-year-old was conscious at the time of his departure from Tropicana Field and Blue Jays players later said he remained responsive to the medical staff while laying face down on the ground after the incident.
"From what it sounds like so far, he's in stable condition, he's conscious and that's all we know so far," Blue Jays right fielder Jose Bautista said. "We're hoping he recovers well and it doesn't get serious. There's always a chance of concussion when you hit your head like that, and we're hoping he doesn't get any symptoms like that."
The incident occurred during the second inning, when Desmond Jennings hit a scorching live drive up the middle. Happ didn't have time to react and the ball hit the side of his face as the sickening sound of impact could be heard throughout the stadium. The ball ricocheted up the right-field line and Jennings made it to third as two runs scored.
Happ immediately dropped to the ground while holding his left ear. Replays would later show that when he removed his hand, there was blood that appeared to be coming from either the left side of his face or ear.
When play eventually was suspended, the Blue Jays' medical staff was immediately joined on the field by a team of on-site medics. Happ was placed onto a stability board, his head and neck were immobilized and he was then removed from the field on a stretcher.
Many of the Blue Jays' players had a look of disbelief and shock. The same could be said for Jennings and his Rays teammates, as the crowd at Tropicana Field remained silent as the situation unfolded on the field.
"He was responsive, he was responsive and talking to the guys," Blue Jays catcher J.P. Arencibia said. "I didn't want to go out and touch him and maybe roll him over and do something I didn't need to do. I don't have any education on that.
"So the biggest thing was, you're trying to ask him, you know he's not okay, you're trying to hear if he's talking, he was talking and then the medical people were out there right away."
The situation was reminiscent of former Oakland right-hander Brandon McCarthy being struck in the head during a game against the Angels on Sept. 5, 2012. Happ's injury also took place on the 56th anniversary of Indians pitcher Herb Score being struck in the face by a line drive hit by Gil McDougald of the Yankees. Score missed the rest of the 1957 season.
McCarthy was able to walk off the field under his own power, but was later diagnosed with a skull fracture and brain contusion. He underwent intensive surgery, but is back in the big leagues this season, pitching for the D-backs.
The Blue Jays will now have to wait for the results of Happ's medical tests and simply hope for the best. It's a situation that clearly had an impact in both dugouts, as the final result of a game -- a 6-4 Blue Jays victory -- was put on the back burner for at least one night.
"Really hope for him and his family everything's well, for the Blue Jays," Rays manager Joe Maddon said. "It was a really scary moment and I trust that he's going to be fine. It puts some perspective on losses, too."
There was plenty of confusion and cause for concern during the immediate aftermath of the injury. When the ball bounced into right field, neither the players nor the umpires seemed exactly sure what to do.
Blue Jays manager John Gibbons and head trainer George Poulis made a couple of steps toward the mound, but stopped because the play was still live. Even the players on the field momentarily paused, but eventually continued on as two runners came around to score and Jennings ended up on third base.
That's when play was finally suspended and the Blue Jays medical staff sprinted onto the field alongside multiple on-site medics from Tropicana Field. Play was put on hold for 11 minutes.
"As soon as it hit him, I started praying and then instinct is that you want to run out there and try to help him, but the ball's live, guys are running home," Arencibia said. "So, I was in-between wanting to run out there, trying to stay home and as soon as [Jennings] got to third base I ran out there. By that point, there's nothing I could really do."
There was no immediate word on when the Blue Jays will receive further updates on Happ's condition. The game did go on, but the focus was less on the result and more on just hoping everything is fine with Toronto's veteran starter.
Happ did raise his hand to the crowd just before leaving the field on the stretcher, but that only brought so much comfort to the rest of his teammates.
"That was the first thing we noticed, he moved his legs and his arms," Blue Jays designated hitter Adam Lind said. "But it's tough to even look at a positive from that situation."