He played in just 15 games the rest of the way, hitting .123 over that stretch, to see his batting average fall from .300 to .264 on the season. He ended up playing in a career-low 70 games as a result of concussion-like symptoms
But Span was able to get through it with his mother's help, and has bounced back this season with a solid year so far at the plate and in the field.
"We're always praying together, especially last year," said Span, whose mother is also a pastor. "I spent a lot of hours on the phone with her trying to get through last year and trying to stay positive."
Span grew up in a single-parent home in Tampa, Fla., and excelled at baseball growing up before becoming a standout at Tampa Catholic High School.
He ended up being selected by Minnesota in the first-round of the 2002 First-Year Player Draft, and thanked his mom for making it all possible.
"I feel like I owe her everything," Span said. "She took me to and from all my practices growing up. She was always at all my games unless it was something to do with work or church. She always supported me. She taught me a lot of values, such as hard work, that I still carry to this day."
Span's mother still follows his career closely from Tampa, as she watches almost every game on television and tries to see him play in person at least once a month.
She gets a chance to see him even more during Spring Training, as the Twins train about 120 miles south in Fort Myers.
"If we play 30 games in Spring Training, she probably sees 15 of them," Span said. "Because we're in Sarasota, Bradenton, Tampa and Lakeland, too. She goes to all those games. This Spring Training she came to Fort Myers maybe five times. So, during Spring Training, she's able to catch some games."
It was at Steinbrenner Field in Tampa where Span and his mom made national headlines, when he hit her with a foul ball during a Grapefruit League game in 2010.
It was the first at-bat of the first inning, and he hit a liner into the stands that hit his mom on the fly. Span immediately rushed into the stands to make sure she was all right, and was relieved to see she was doing OK.
"She was just sore for a week or two," Span said. "Thank God I was the one who hit it, because if it was someone else they might've put some extra steam on the ball. So I jumped over the railing to make sure she was OK. But she's a tough cookie."
Span can now smile a bit about that incident, and isn't immune to hearing some jokes at his expense coming from her -- even about last season's struggles.
"She always jokes with me that I messed up her year last year," Span said with a smile. "She said, 'I didn't get a chance to travel because your behind was hurt.' But she's happy I'm playing, and I think when I'm happy, she's happy."
So it's a tight bond between mother and son, and one that stays strong even though he's a big leaguer who plays his home games at Target Field more than 1,500 miles from home.
"With 365 days in a year, I probably talk to her 362 days," Span said. "So we're very close. She's the one person I trust the most. I feel like I can talk to her about everything. With other people I can have a guard up, but with her, I feel like I can say anything I want. I can say it without filtering it. And at the same time, she'll give me her honest opinion back. If I'm wrong, she'll tell me I'm wrong. And that's why I've always respected her."