Green has made major changes

“I wasn’t thinking this could happen, what has happened now,’’ Green said.

Green would have been satisfied with a starting spot in Triple A this season, thrilled with a reserve role for the worst team in the majors. And here he is, halfway into the season, the starting shortstop for the first-place Red Sox, a position rivaled in cachet by few in baseball.

His versatility and good fortune provided an opportunity in spring training. Green capitalized with elite athleticism, a rifle arm, and, maybe most essentially, a relaxed mental state he attained and maintains through atypical means.

“He was in the right place at the right time,’’ Red Sox infielders coach Tim Bogar said. “To his credit, he seized it.’’

Green is well-liked by his teammates, soft-spoken, and quick to smile. Before games, he can’t be still. He fidgets during the national anthem. Sitting at his locker, he reads the paper, does a crossword, or taps the keys on his cellphone, his fingers and mind in constant motion.

“Thank goodness they have phones with the Internet on them,’’ Green said.

Early in his career, Green struggled with a wicked temper, once triggered by the smallest things. He was ejected from his final high school basketball game and his final college baseball game. A shirt would get caught on a hanger, and Green would yank and yank until the fabric ripped. A stubbed toe enraged him. If a car cut him off in traffic, he gnashed his teeth and stewed for hours.

In 2005, when he played for Tampa Bay, a trainer introduced him to Dr. Ken West, an optometrist who moved into performance science. He lives in New Mexico, lectures at Oxford, and has worked with athletes all over the world. He calls himself “an eclectic database,’’ and his aim, he says, is to unlock human potential. Green thought he was strange.

West and Green have worked together and have become close friends, and Green gives him partial credit for his success. West identified causes repressing Green’s potential. Green placed too much pressure on himself. His inability to meet unrealistic expectations frustrated him. Anger clouded his ability.

“We’ve been on a mission with Nick for the last few years to find factors that crop up when he is getting in his own way,’’ West said in a phone interview. “And then we eliminate them from his subconscious.’’

Green said West is able to clear mental blocks and boost his confidence. He does that through a number of varied and unusual processes. One of them works like this: Green and West will talk about a problem until they discover the root of it; it may stem from Green’s childhood. Green will place one hand on where the related emotion originates - the liver is anger - and the other hand on his head. Green breathes in a pattern while West taps specific vertebrae.

West utilizes another process he calls “paradoxical limbic programming or deprogramming.’’ Sometimes he uses digital 3-D imagery and a liquid Green drinks. It’s hard to summarize.

“He works with brain waves and stuff,’’ Green said.

Green also calls on West’s devices to heal injuries, which West believes derive from emotions. During spring training in 2006, turf toe sidelined Green. Trainers worked on the injury for weeks to no effect. Green called West, and days after he flew to Florida, Green felt healed.

“A lot of the pain you have is through emotions,’’ Green said. “If you clear the emotion out, the pain starts healing. A lot of people think it’s a hoax. The thing is, it makes me feel great about myself. I wish he was around all the time. He’s the most positive guy I’ve ever been around.’’

Green calls West roughly every three weeks and sees him in person roughly every six weeks. Green referred Jason Giambi, his teammate with the Yankees in 2006, to West, and now Giambi employs him. (West called Giambi his “only rock star hooligan’’ out of the athletes he works with.) West plans on flying to Boston to work with both of them when the A’s come to town next week.

“He can reset me through the phone, but it doesn’t hold,’’ Green said. “When he does his thing in person, it holds.’’

Green’s progress with West didn’t eliminate his stress. Green played only six big league games with the Mariners in 2007, and he returned that offseason to the Yankees, with whom he played 46 games in 2006. After spring training last year, Green realized he would not play in the big leagues. The sting metastasized. He watched teammates get called up while he stayed in Scranton/Wilkes-Barre, and wondered why. He put pressure on himself. He lost confidence.

“My mind was clogged up with garbage,’’ Green said. “It’s kind of tough to overcome anything if you have negative thoughts in the back of your head.’’

Green escaped his funk by August, but he still hit .233 for the season in 112 games. He scanned rosters last offseason not in hopes of earning a big league spot, but with a question in mind: If someone got hurt, where might he have a chance to be called up from Triple A?

Boston fit. Red Sox special assistant Allard Baird liked Green’s potential and recommended him to general manager Theo Epstein. Green signed a minor league contract and arrived at spring training as a nonroster invitee. His career stats - a .240 batting average and 10 home runs in 275 games - suggested he would become spring fodder.

Right away, his throwing arm - “one of the best I’ve ever seen,’’ Bogar said - impressed manager Terry Francona. Whenever the Red Sox needed a spot filled, Green was there - he has played every position but pitcher and catcher in his career. When Julio Lugo was injured and Dustin Pedroia went to the World Baseball Classic, Green played with enough frequency and efficacy to earn the most improbable spot on the Opening Day roster.

Green, 30, has never played better than he is this year. He hit a walkoff home run last week. After a rocky start on defense, his consistent playing time has helped him extend an errorless streak to 97 chances even as his athleticism allows him to reach balls other shortstops could not.

Green’s temper has disappeared, but he still confronts his own doubts. He tries to focus on the moment. But when he plays poorly for a game or two, he sometimes thinks, “What do I do? I have to get back.’’

“The stuff that creeps more into my head is stuff that shouldn’t,’’ Green said. “I start putting too much pressure on myself. I’m not immune to that. I try to block it out the best I can.’’

His career has conditioned Green never to feel comfortable. Only months removed from a full season in the minor leagues, Green knows any position may not last. He also knows he is in a good place, better than he could have imagined.

“I’m extremely happy,’’ Green said, “that I’m here.’’