It was Hosmer who, on June 15, 2013, rocked a line drive off the side of Cobb's head in a game at Tropicana Field, sidelining the Tampa Bay right-hander for two months with a concussion.
"You know, that doesn't cross my mind," Cobb said. "When he's in the box, I'm not thinking of -- I'm not having flashbacks or anything."
Really? He wasn't thinking about that line drive -- which collapsed him to the turf, brought the Rays infielders rushing to surround him and sent head athletic trainer Ron Porterfield sprinting onto the field, waving everyone away -- at all?
"No, no. I really wasn't," Cobb said. "Just, there's so many other things going on in the course of the game that you don't let that thought cross your mind."
So there were no old ghosts haunting Cobb when, in the top of the first inning of the Rays' 5-4 loss to the Royals Wednesday night, he went into his twisting, hitchy windup and delivered his first pitch to Hosmer since he was stretchered off the field last June.
The 92-mph fastball spun off Cobb's fingertips and ran, belt-high, over the middle of the plate. Hosmer launched it.
Right fielder Kevin Kiermaier turned and ran a few strides back to the warning track, then watched the home run sail well into the right-center field seats.
That's when, just briefly, Cobb recognized who had hit it.
"It's something that you think about after he hit the home run, maybe -- like, 'Dang, that guy's hit me really well, and I would like to get him out.'"
As catcher Jose Molina tossed Cobb a new ball, Cobb snapped his glove at the throw in frustration.
"Well, yeah, I was [mad] -- I just gave up a run. I was mad to give up a run, for sure," Cobb said. "But it wasn't because it was Hosmer. If any of the other eight batters were to hit a home run off me in that inning, I would have felt the same way. It wasn't anything because of him."
David Adler is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.