Angels pitcher Scott Kazmir is back, but has he returned?

Reporting from Tempe, Ariz. — His shoddy 2010 season is as much a sore subject for Scott Kazmir today as it was for those who watched it last summer, when Angels management and fans wondered whether the left-hander would ever right himself.

Kazmir didn’t even look at tape over the winter to determine what went wrong because the whole season was a mess, from hamstring and shoulder injuries to mechanical problems to a loss of velocity on his fastball and the disappearance of his slider.

“I pretty much did away with last year,” Kazmir said this week in Angels camp. “I don’t want to talk about my struggles, my slider. I just want to go out there and compete and win games.”

Two years removed from a superb 2008 season in which he helped Tampa Bay reach the World Series, Kazmir was 9-15 with a career-worst 5.94 earned-run average in 28 starts. He struck out a career-low 93 and gave up a career-high 25 home runs.

Kazmir had been considered one of the best young left-handers in the game; he was 13-9 with a 3.48 ERA and an American League-leading 239 strikeouts in 2007 and earned a three-year, $28.5-million contract from the Rays before 2009.

He is only 27, but if Kazmir doesn’t regain some zip on his fastball, which slipped from the 94-mph range to 89 mph, find his slider and command those pitches along with his changeup, he will be in danger of being released or demoted to the bullpen.

Hisanori Takahashi is primarily a reliever, but the Angels acquired the left-hander because he has extensive experience as a starter and can provide rotation insurance if Kazmir stumbles.

“This is a big year for me,” said Kazmir, who is entering the final year of a contract that pays him $12 million this season. “I feel like I have something to prove. That wasn’t me last year.”

Kazmir lost the bite on his slider late in 2009, when the Angels acquired him from the Rays, but he still had good enough command of his fastball and changeup to post a 2-2 record with a 1.73 ERA in six starts.

A hamstring injury sidelined Kazmir for most of last spring and the first two weeks of the season. His 2010 debut was a four-inning, six-run, eight-hit loss against New York in Yankee Stadium on April 15, and his season spiraled from there.

By early July, Kazmir was back on the disabled list because of shoulder fatigue. At the time, he had a 7-9 record, a 6.92 ERA and couldn’t throw a decent slider, which in seasons past had been lethal against right-handed hitters. A few decent September starts spared him the indignity of a six-plus ERA.

“I got to a point in the season where I didn’t have range of motion and was almost manipulating my body just to get the ball over the plate,” Kazmir said. “I was trying to compete, to battle.”

There were lengthy meetings with Manager Mike Scioscia and pitching coach Mike Butcher, hours in the video room, constant tinkering with mechanics, extra work in the training room. Nothing seemed to help.

“He was certainly searching,” Scioscia said. “I think he became more max effort last year, which hurt his location and command as he tried to find velocity. The fact he wasn’t spinning the ball as well with his slider was not as big of an issue as his inability to hit spots with his fastball and bring his changeup into play.”

The team insisted Kazmir, who lives in the Houston area, begin training at a specialized physical therapy center in Arizona on Nov. 1. His career now on the line, the pitcher had little choice but to oblige, and he spent 31/2 months in Tempe focusing on improving his arm strength, flexibility and balance.

He reduced his body fat from 13% to 9% and began his throwing program earlier, completing 12 bullpen sessions before camp. It’s early, but he likes the way the ball is coming out of his hand.

“I noticed a big difference in strength and range of motion,” Kazmir said. “I feel real good right now.”

The Angels have four good starters in Jered Weaver, Dan Haren, Ervin Santana and Joel Pineiro. How Kazmir pitches could determine whether the rotation is very good … or great.

“To get Scott back to the form he was when he first came into the league would be huge,” Weaver said. “It seemed like he didn’t trust his stuff last season, but he’s feeling healthy now. I don’t think he needs to reestablish himself for the club’s sake, but for his sake. It will be good for him to show he’s still got it in him.”

mike.digiovanna@latimes.com