Then, something changed, and he'd love to know what. His home run total dropped to 11 this season, and he's currently batting .162, which is 90 points below his career average and 98 points below what he hit last season.
He's changed his bat company, type of wood and the color of his lumber. He's tinkered with his swing and talked to the team psychologist, but nothing's worked. In 110 games this year, he's had a total of 16 in which he didn't strike out. He's had 21 where he struck out three or more times.
Any batter will tell you that slumps are part of the game. "But not like this," Dunn said in May. "This is ridiculous." His average has dropped 27 points since he said that.
In June, he said, "I don't even answer my phone anymore, because I don't want to hear what's wrong. It's frustrating—I can't even put it into words." His average has dropped 16 points since then.
During his playing days, Dunn's manager, Ozzie Guillen, resorted to putting eyedrops on his bats during dry spells so they might see a hit. Dunn's teammate on the 2002 National League All Star team, Barry Bonds would get so frustrated during slumps he would sit at his locker and cry.
"I was a ballplayer," Duke football coach David Cutcliffe said of his days on the diamond, "and slumps are a very difficult thing mentally. I knew I was a good hitter, with a fine swing. You don't want to start thinking about your swing."
"It's like golf," Cutcliffe added.
For four years, David Duval was the best player in golf. He reached number one in the world golf rankings in 1999, won 13 tournaments from 1997 to 2001, and tied a record with a score of 59 in one round. Duval finished second in the Masters twice, and capped it off with a win at the British Open.
Then something changed.
Duval would eventually reach 1054 in the rankings he once topped. He hasn't won in nearly a decade and has had some horrific days on the links.
At the 2003 PGA Championships, he shot an 80 on the first day, then opened the second day with a triple bogey, double bogey, and bogey in his first four holes. He walked off the course and headed for the airport.
"I never understood why golf was so hard for people," Duval told Golf Digest in the midst of his slump. "I do now. I've struggled with it…I never thought that would happen to me, hitting the ball so poorly and having all those negative thoughts."
Duval struggled with injuries, both serious and nagging. He changed his stance to compensate for the injuries, then changed it back to try to recapture the magic. "I was a disaster," he said.
Something has changed for Will Snyderwine.
Last year, the Duke kicker was an All American and a Groza Award semifinalist for the second straight year. He was Duke's most accurate kicker, hitting 38 of 44 for his career, which put him 131 percentage points ahead of the Sims Lenhardt, who kicked for the Blue Devils in the late 1990s.
Lenhardt has had a heck of a year in 2011, closing to within 59 points of Snyderwine's lead.
Going in to the season, Snyderwine had just one game in 23 where he'd missed more than one field goal. He'd kicked at least two successfully in 11 of his last 14 games.
This year, Snyderwine is still looking for his first make. He missed two potential game winners in the closing minutes of the opener, including a 28 yarder, his shortest miss since his first career kick.
In the Stanford game the following week, Snyderwine missed another pair, including a 27 yarder. He has more misses in two games than he had in any previous season. He has as many games with no field goals as he had in his previous 17 games.
Like Duval, Snyderwine has had a nagging injury. "He's had a small ankle issue," Cutcliffe said. "Now trainers tell me it's much worse."
Snyderwine injured his ankle on an onside kick, and it looks like he might miss some time. That might be the best thing for the struggling kicker.
"I can't put my finger on it," Snyderwine said after the Stanford game. "Nothing's really broken."
The frustration seemed to get the better of him after his fourth miss of the season. "I walked out there confident," he said. "I ran through all the normal reminders. Sometimes, it just doesn't go your way."
Snyderwine threw his arms up in disgust on the sidelines, then decided he needed some advice.
"I went up to (Coach Cutcliffe) on the sidelines to see what he had to say," Snyderwine said. "He's a wise man, and I trust him. He told me it's a work in progress."
"I told him, ‘You're not suddenly a bad kicker,'" Cutcliffe said. "It doesn't work that way. It's just a very difficult thing, mentally. I told him, ‘You went out there worried about missing it instead of enjoying what you're doing.'"
"The last thing I want to do is panic about our kicking game," Cutcliffe added.
Of course, panic is exactly what Snyderwine is fighting.
"I hope we can get him well," Cutcliffe said.