Such was the extent of the concussion symptoms that d'Arnaud experienced last week, after taking an Alfonso Soriano backswing off the top of his helmet. Extremely sensitive to light and sound in the days that followed, d'Arnaud endured "a lot of headaches" and struggled to sleep.
It is a concern for the Mets, even though d'Arnaud feels better now and has been cleared for full baseball activities. This concussion was the third of d'Arnaud's professional career, following similar episodes in 2011 and '08. Previous concussions typically make athletes more susceptible to future ones, prompting the Mets to explore ways to protect their starting catcher.
At the beginning of last season, the organization asked d'Arnaud to shift a bit further behind home plate. They also encouraged him to continue using the hockey-style goalie mask that he adopted in the Minors, though d'Arnaud now hopes to switch back to a traditional helmet with detachable mask.
Regardless of those factors, d'Arnaud knows he will always be at risk. In the wake of his latest concussion, he took solace mostly in the fact that Soriano's backswing was abnormally long and violent -- the type that catchers do not often experience.
"Anytime you have a guy that says, 'Hey, I've got three concussions,' you've got to worry about it," Mets manager Terry Collins said. "But that was a pretty freakish thing."
For the next two to three days, d'Arnaud will participate in baseball activities under the watchful eyes of Mets staff members. Doctors must fully clear him before he can come off the disabled list, in a process that could drag into the weekend.
In the interim, Anthony Recker and Juan Centeno will continue splitting time at catcher.
Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.