From 2006 to 2012, Dan Uggla hit 209 home runs, 46 more than any other major league middle infielder. He was the best of a rare baseball breed, a commodity any team would covet: a power-hitting second baseman with more home runs in that span than all but 10 players in the major leagues.

Few would have predicted that such a player, orthopedically healthy and untouched by scandal, would find himself anywhere but on a major league field by August 2014. No one would have predicted he would find himself blindfolded and bouncing on a trampoline in a doctor’s office in Las Vegas.

But for two weeks in August, that is exactly where Uggla was, cut by the Braves and then the Giants after an improbable two-season descent into offensive and defensive futility. Now the three-time all-star is in Washington Nationals camp as a non-roster invitee, hoping his unorthodox offseason will rejuvenate his career after he hit .149 with two home runs and 46 strikeouts in 141 at-bats last season.

“Playing against him the last few years, it looked like a guy not trusting what he’s got.” said Nationals hitting coach Rick Schu, who coached Uggla in the minors for the Diamondbacks after Arizona and then-scouting director Mike Rizzo drafted Uggla in 2001. “It didn’t look like he was seeing the ball.”

Robert Donatelli, a well-known sports physician who trained such athletes as tennis player Andy Roddick and former all-star outfielder Marquis Grissom, saw the same thing on television, called Grissom and said, “I think I know what’s wrong with Dan Uggla.”

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Donatelli trains willing athletes to improve their vestibular system — colloquially known as the inner ear, the system that controls balance. That system aids the eyes in focusing on a target even while the body and head are moving. Dysfunction in the vestibular system can affect an athlete’s ability to see things in motion, such as a baseball hurtling his way while his head and body are rotating to hit it.

Head trauma can cause dysfunction in the vestibular system. Uggla was hit in the head by a pitch in July 2012 and again in the back of the head by a pitch during spring training in 2013. Uggla himself did not definitively classify his reaction as a concussion, and Donatelli said Uggla did not have the symptoms — dizziness, nausea, etc. — that would have alerted the Braves that any kind of severe head trauma had taken place.

Knowing that, Donatelli asked Grissom for Uggla’s number.

“He called and he [listed] a lot of the symptoms that hit dead on with me,” Uggla remembered. “I was like, ‘How soon can I get out to Vegas to see you?’”

When Uggla got there, Donatelli ran him through 12 tests that helped assess his vestibulo-ocular reflex. Uggla failed them all. Donatelli moved Uggla’s head to the left and right and asked him to read an eye chart. Uggla, who had Lasik surgery when he initially had trouble seeing the ball in 2012, had 20-15 static vision. With his head moving, that vision dropped to 20-100.

“I can’t tell when I’m sitting here talking to you. Before [going to Donatelli], I would think I can see you just fine,” said Uggla, who will turn 35 in March. “But I guess when I get on the baseball field and my head starts moving around . . . it was kind of bad.”

Donatelli pushed Uggla through exercises such as jumping on a trampoline blindfolded or reading while moving his head. Those movements isolated Uggla’s vestibular system and forced his eyes and inner ear to recalibrate.

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Uggla spent two weeks working out twice a day at Donatelli’s office, then doing a home program in his hotel room each night. Then he went home to Atlanta and continued his work for the next two months at a facility manned by trainers well-versed in Donatelli’s methods.

“It’s been a gradual process, so it’s hard to see a sharp change like, ‘Oh man, I can see!’ ” Uggla said. “But from where I was to where I am now, I can definitely tell a difference.”

Though he says he sees the ball better now, Uggla will not say those vision problems contributed to his rapid decline.

“I’m the one that was in the box,” Uggla said. “It’s been very tough to see the ball the past couple years, but is that because of [the vision]? Or is that because I was in bad habits? Who knows?”

Either way, Uggla is glad for the opportunity with Washington — though he admits the Nationals’ situation changed when they traded for Yunel Escobar, presumably to be their new everyday second baseman.

Manager Matt Williams said the second base situation “isn’t necessarily a competition, but we’ll look at everybody.” Rizzo, now the Nationals’ general manager, said Uggla has “to be the best second baseman in camp to win the job,” which would mean beating out Escobar and plus-defender Danny Espinosa.

In order to do that, Uggla would likely need to show beyond any doubt that he is the 30-homer player he once was and that his defense — always questioned but seemingly even more suspect the past two seasons — has improved, too.

After a week of watching him hit, Schu says he thinks Uggla “is getting in much better position, giving himself a chance.” Uggla, who doubted at times that he could still play the game at all, says he now believes “100 percent” that he can be the player he was. He will get plenty of at-bats this spring. If he is ready to bounce back, the Nationals will see that. Uggla will be able to see it, too.

chelsea.janes@washpost.com