The Rays announced during their game against Kansas City that Cobb had been released from Bayfront Medical Center in St. Petersburg. The team said he will be placed on the seven-day concussion list.
There was no timetable for when Cobb will rejoin the rotation.
Cobb texted teammates Sunday morning, including pitcher Matt Moore, saying he had a headache but would soon be out of the hospital.
In a message posted on his Twitter account, Cobb thanked Rays head athletic trainer Ron Porterfield and the doctors at Bayfront, and said that he "woke up with only a minor headache."
Cobb was struck by a liner off the bat of Kansas City's Eric Hosmer in the fifth inning of Saturday's game but remained conscious the whole time. He was taken off the field on a stretcher.
"I think he was very happy to see how many people wanted to come and see him," Moore said.
It was a tough week for Cobb, who left the team after starting Monday night's game against Boston due to the death of his grandmother. He was informed of the death after the game in which the 25-year old gave up a season-high six runs over four innings in a 10-8, 14-inning loss to the Red Sox.
This latest incident of a pitcher being hit by a batted ball is sure to spark more discussions about new pitching protection equipment.
"Whoever comes up with the solution for this, they're never going to have to work again in their lives," Rays pitcher David Price said. "It's scary. We know about that. You think about it, and then you don't think about it when you're on the mound. But when you see it happen, and you see line drives and hard groundballs up the middle, it definitely cross your mind."
Moore said he would be willing to wear headgear if it was developed.
"A cricket helmet, or whatever it was, I would give it my best effort to make sure I pitch with that," Moore said. "If I could prevent something like that by wearing something, without a doubt I would."
The incident involving Cobb was the fifth time in the last five months of regular and postseason major league action that a pitcher has been hit in the head by a liner and the second such episode in a game this spring involving the Rays at Tropicana Field, as last month Toronto's J.A. Happ was hit on the left ear by a shot off the bat of Tampa Bay's Desmond Jennings.
Beginning with then-Oakland Athletics pitcher Brandon McCarthy suffering life-threatening head injuries when struck by a ball off the bat of the Los Angeles Angels' Erick Aybar on Sept. 5, four of the five incidents involved contact below where a cap covers the pitcher's head. MLB says it is actively trying to come up with a protective cap, with padding to decrease the risk of injury on balls that hit above the cap line -- but no efforts are underway to achieve broader protection of the head.
Chris Young, now a pitcher for Washington's Triple-A Syracuse Chiefs farm team, told "Outside the Lines" before the Happ and Cobb injuries that MLB should consider headgear with more coverage than caps, as catastrophic injuries because of the exposure of the face, eyes and temples are a deep concern.
Young has graphic firsthand experience with shots to the head.
In 2008, when he was pitching for the San Diego Padres, Young was struck between the eyes by an Albert Pujols liner and suffered a fractured skull, fractured right orbit and deviated septum. He said protective headgear including a visor, along the lines of what is worn in hockey, would've been beneficial, and he noted that the helmets batters wear don't protect the eyes and the face. He added that catchers are the only players who don headgear that comes close to full protection.
Young said padded caps could be a good first step toward helping reduce the injury risks, and that pitchers accept their profession's inherent danger, but that without further measures of protection, "somebody will die from this."
Information from ESPN's Willie Weinbaum and The Associated Press was used in this report.