Angels’ Dan Haren has been delivering this spring

TEMPE, Ariz. — He’s not the ace, not the flashy new free-agent signee, and he hasn’t been an All-Star the last two seasons.

But don’t be surprised if Angels pitcher Dan Haren has a career-best season.

Yes, you can asterisk everything that’s happened in the last few weeks with the notation “It’s only spring training,” but the 6-foot-5 right-hander has at times appeared unhittable.

Here are a few highlights from his recent starts:

March 12: Strikes out seven Arizona Diamondbacks in three innings, including the heart of his old team’s order — Justin Upton, Miguel Montero and Chris Young — and whiffs the final three batters with 10 pitches.

March 18: Extends his streak of 21 consecutive retired batters and counts 15 strikeouts through 10 innings by opening with four perfect innings against the Dodgers.

“Bad swings, surprising looks … I’m happy with how the opposing hitters have looked and taking that confident feeling into the season,” Haren said afterward.

March 23: Has a rocky fourth inning and gives up his first multiple-run frame but is content about minimizing the jam with another strikeout in his first game with new catcher Chris Iannetta. Through 202/3 spring innings, he has struck out 20 and walked only two.

Wednesday, Haren complained of a spring “dead arm” in scuffling through five-plus innings, predicting he’ll be back to form perhaps as soon as Monday’s Freeway Series opener against the Dodgers at Angel Stadium.

Haren said that in addition to focusing on his mechanics and delivery this spring, he has worked to improve the way his fastball runs in on right-handers.

“You have to be able to throw a nice, hard fastball to a righty,” Haren said. “I have more in the tank. I’ll let it go more [now] at the end of spring.”

He’s also mixing in more curveballs and split-finger pitches after relying on cut fastballs for as many as half of his pitches last season.

Mike Butcher, the Angels’ pitching coach, predicted Haren’s success this season would hinge on the quality of his pitches and his proven endurance.

Haren didn’t miss a start last season, totaling 34, and going 2381/3 innings with a 3.17 earned-run average. His 237 starts over the last seven seasons are the most in the major leagues.

Butcher said Haren, a La Puente Bishop Amat High and Pepperdine product, also has the makeup a title-contending team requires.

“He’s as good of a guy as you can ask for — [character] off the charts,” Butcher said. “Quality guy, inside and out. Tremendous competitor. A leader. Everything you want from a starting pitcher: durable, a guy to rely on.

“And we’ll be relying on him heavily.”

The feeling is mutual, considering the Angels have the option to keep Haren in 2013 for $15.5 million.

Angels Manager Mike Scioscia said Haren has been especially strong this spring in jumping ahead in counts, 0-1 and 0-2.

If Haren could hit 94 mph with his fastball as he did five or six years ago, he would throw the pitch more often. But the mileage that comes with not missing a start in seven years has taken a toll on his fastball, which is now in the 89-mph vicinity.

“My game is location, control, keeping hitters off balance,” Haren said. “I’m just trying to miss barrels. Whether it’s a two-seam fastball that runs a little bit or a cutter that moves three or four inches to get it off the barrel, that’s the difference between a home run and a fly ball or ground ball.”

Understanding that game of inches, and successfully executing it, could take him and the Angels a long way.

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