Eisenlohr, a 24-year-old graphic designer from Pennock, Minn. (about an hour away from the Twin Cities), caught Thomas' milestone 500th home run in the first inning of the Jays' game with the Twins. About 15 minutes later, Eisenlohr turned the ball over to Thomas for an autographed jersey, bat and ball.
The Twins fan, who sported a Jason Bartlett jersey, was at the game with his parents to celebrate the birthday of his mom, Kathy. He said the ball was easily in reach when it cleared the left-field wall.
"I just kind of leaned over. If I didn't catch it, it probably would've hit my dad in the head," he said.
Eisenlohr was sitting in row five of section 101 when the ball came to him, and was aware of the significance of the home run when he caught it.
"I was watching the games on TV and they were talking about [Thomas] hitting 500," he said. "After I caught it, everyone was giving me high fives."
With Twins pitcher Carlos Silva struggling early against the Jays, Eisenlohr's father Lyle knew the time might be right for history to be made.
"They started hitting on Silva and I saw Frank Thomas was about to come up, and I told my wife, 'The way Silva is pitching, Frank Thomas has a chance at hitting a home run.' The next thing I know, the very next pitch, here it comes," the elder Eisenlohr said.
While Eisenlohr said he might try to sell the jersey he received from Thomas because "it's a Blue Jays jersey," he did say he plans to keep the bat and ball and that he had no thoughts about parlaying his new possession into a financial gain by selling the ball to Thomas or the Jays.
"I don't really care about that. It's just money," he said.
Thomas said he appreciated Eisenlohr's willingness to give up the ball without asking a king's ransom.
"That was very classy of him, he was very gracious. He's a nice guy," Thomas said of Eisenlohr.
As for the ball? It will stay with Thomas, unless a certain institution focused on baseball history comes calling.
"I'm going to keep it unless the Hall of Fame wants it," Thomas said. "If they want it, I will probably give it to them."
Joe Kieser is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.