Erick Aybar’s MRI reveals slight strain in his left side

He has sat out three games with what the Angels had been calling muscle tightness in his left side, and now infielder Erick Aybar has undergone an MRI that revealed a slight strain, according to Manager Mike Scioscia.

“Right now we’re hoping it’s not a [disabled-list] situation,” he said of Aybar, who had the exam Wednesday morning.

Scioscia said it’s unlikely Aybar will be well enough to start Friday in the home opener at Angel Stadium, but he could be available to pinch-run or pinch-hit over the weekend.

“We’ll evaluate it,” he said. “He’s only been able to bunt. We’ll see how he is Friday, if he can maybe be part of the game a little bit more if we need him to do something.”

Although Aybar played a career-high 138 games last season, he was bothered by injuries for most of the summer, missing time in June because of a hyperextended left knee and in September with what the Angels called a sports hernia.

As a result he hit .253, 21 points below his career average, and committed a lifetime-worst 21 errors before having minor surgery on his knee in October.

Aybar’s most recent injury occurred on a head-first slide into third base in the eighth inning of a loss to the Kansas City Royals on Saturday. Maicer Izturis replaced Aybar in the field the first two games and Brandon Wood played shortstop Wednesday.

Coming of age

The Angels have a rookie closer, a rookie first baseman and a regular starter in center field who had less than two months of big league experience coming into the season. And none of the pitchers in the starting rotation is older than 30.

“It’s a youthful, talented group that we have high expectations for blended with some very, very good — some terrific — veteran players,” Scioscia said. “It’s a great blend.”

And with an average age of 28.3 years, it’s also the fifth-youngest roster in baseball and the franchise’s youngest since the World Series year of 2002 — though the average age of that team was skewed a bit by late-season call-ups from the minor leagues.

“Last year we were young for a while,” Scioscia said. “This year there’s some young guys that are getting an opportunity and are going to be important to us.”

Youth may not be served for long, however. The Angels’ roster will age with the return of 35-year-old reliever Scott Downs and 32-year-old right-hander Joel Pineiro from the disabled list, which is expected to happen later this month.

On the mend

Downs, sidelined because of a broken toe, will pitch for Class A Inland Empire in the team’s California League opener Thursday night. Scioscia said Downs probably will need at least one additional rehab appearance before he is reactivated.

Meanwhile Scott Kazmir, who is scheduled to start Saturday at Angel Stadium, was on the field early Wednesday throwing the ball from the warning track in right-center field to the Angels’ bullpen in the left-field corner, a distance of more than 300 feet. Kazmir, who was throwing to pitching coach Mike Butcher, said the exercise is designed to help him keep his arm strong and his throwing motion free and easy.

“That’s the whole point of long toss,” he said. “So when you get back to [throwing] 60 feet you feel like you’re just touching the guy you’re throwing to.”

kevin.baxter@latimes.com