The Red Sox have decided to bring Tim Wakefield back to Boston for a 15th season.

Yesterday afternoon the Red Sox exercised the 2009 option on the right-handed knuckleball pitcher’s contract, worth $4 million. The 42-year-old was 10-11 with a 4.13 ERA in 30 starts for the Red Sox in 2008.

“I’m ecstatic,” said Wakefield about returning. “I feel great. My physical went well.”

His personal batterymate, backup catcher Kevin Cash, also welcomed the news.

“What he’s done the last couple of years, and the innings he provides — everybody realized during the season he was a .500 pitcher who could have easily had more wins if we had some things go our way,” said Cash. “What he provides for the entire pitching staff makes him pretty valuable.”

Because of Wakefield’s age, and due to some of the health issues he’s dealt with in recent seasons, some might think the seasoned veteran is close to the end. He doesn’t feel that way, and Cash doesn’t think so, either.

“A lot of people think because he throws the knuckleball that he doesn’t have to work as hard as the next guy or as a more conventional pitcher and, to an extent, I understand where people are coming from. But also you have to take the approach that he’s 42 and to maintain that six-month grind of the season, he still has to put the work in. I know he works out hard during the offseason and last spring it looked like he came to camp in as good of shape as anybody. His work and effort level is still the same.”

Because he obviously doesn’t throw the ball like, say a Josh Beckett, Wakefield’s unique pitch, and his success with it, has given him longevity.

Wakefield is second in club history with 1,797 strikeouts, 367 starts and 504 appearances. He’s third with 164 wins and 2,581 2/3 innings. In fact, he’s the only Red Sox pitcher with at least 500 games and 350 starts in his career. Also, his 14 seasons are the longest continuous stint for any pitcher in club history.

Having Wakefield back in the mix is also a good thing for Cash.

Cash, 30, became Wakefield’s personal catcher during spring training when he proved he could handle the role. As a result, the club released Wakefield’s longtime batterymate Doug Mirabelli.

The Red Sox still own the rights to Cash, but he’s arbitration eligible. According to Cash, neither he nor his agent have had discussions with GM Theo Epstein.

“They have some very important decisions to make with some other guys before they concern themselves with me,” Cash said.

Still, he feels very good that Wakefield is returning.

“Without a doubt,” Cash said. “Definitely. But at the same time, I’ve played long enough to know that just because they did something for one guy doesn’t means that it’s going to pan out for you. My circumstance is different from everyone else’s. I can’t compare myself with Wake or another catcher. I just have to worry about my situation. I’m sure I’ll hear from them soon. I’m definitely happy they picked up [Wakefield’s option] because, if anything, it helps me.”

Cash caught all 30 of Wakefield’s starts in 2008 and posted a career-high .225 batting average in 61 games, including three homers and 15 RBI.

In a not-unexpected move, injured pitcher Curt Schilling yesterday filed for free-agency.

jmcdonal@projo.com