Fortunately, Jennings appears to be fine. He does have a concussion, but avoided a more serious injury.
"As a pitcher, it's one of our worst nightmares," closer Steve Cishek said. "I don't even want to look at video, because you don't want it to be in your head. And having that being one of your teammates and friends, you know their families are also watching, and they're scared too. You feel for them, too. You've got all these emotions going when something like that happens."
What can be done to increase pitcher safety?
"I don't know if there is anything you can do, other than putting like a mask or something on," reliever Mike Dunn said. "I can pretty much guarantee nobody is going to wear [one]."
Alex Torres of the Padres is the first and only pitcher to wear an MLB-approved protective cap, manufactured by isoBlox.
But the hat is bulky, and many pitchers don't find them comfortable. Another idea some pitchers are discussing is a hat with ear flaps to protect more of the head.
"I know they're trying with those big, bulky hats," Cishek said. "The problem is they're just not comfortable to wear, and they're heavier.
"You've got to wait for the technology to get out there, and hopefully some day it will, where we can get out there and not wear a hat that is big and bulky, and is little lighter and comfortable. At least they're moving in the right direction and trying to figure something out."
In the meantime, pitchers are focused on one thing when they take the mound -- getting batters out.
"You know there is a risk every time you go out there and throw a pitch," Dunn said. "Ultimately, you've just got to put it behind you and not think about it."