The Red Sox continued the fine-tuning of their roster yesterday with not only the official addition of Penny but also the apparent retention of outfielder/first baseman Mark Kotsay. Both veterans will receive one-year contracts, in keeping with general manager Theo Epstein's recent moves.

The Sox, according to a source, believe they have a formal agreement in place that will bring Kotsay back. Kotsay is vacationing in the Caribbean, and his deal can be finalized only after he returns and completes a physical.

Penny's contract, according to a source, is worth $5 million, and performance bonuses - starting at 160 innings pitched - could add $3 million. Penny's signing falls in line with other Red Sox deals following their failed pursuit of free agent first baseman Mark Teixeira. He's a low-risk, high-reward complementary player who, ideally, will bolster the Sox' depth.

Penny, 30, endured his worst season last year with the Dodgers, owing to three trips to the disabled list, all because of a right shoulder injury. He went 6-9 with a 6.27 ERA in 19 games (17 starts) while striking out 51 and walking 42 over a career-low 94 2/3 innings. Penny, though, offers the potential of a nine-year veteran who was selected for the All-Star Game in 2006 and 2007, when he went 16-4 with a 3.03 ERA.

Penny chose the Sox over a handful of teams from the National League, he said, for three main reasons: The Sox gave him the best chance to win; the renowned shoulder program of trainer Mike Reinhold; and to reunite with Beckett and Lowell, with whom he won a World Series as a Florida Marlin in 2003.

Penny feels this can serve as vindication for last year, when he rushed back from a shoulder injury. While on the disabled list, he played catch when he shouldn't have. Each time he returned, he knew it was too soon. He hated watching his teammates play without him.

"To me, going out there and doing that is embarrassing," Penny said. "That's not the Brad Penny last year. I do feel I have something to prove."

Which is why Reinhold's program, Penny said, was "a huge factor in my decision." He had been familiar with it before visiting Boston, and Beckett helped convince him it would help return him to the form that made him one of the NL's best starters. Penny expects his shoulder will not affect his preparation once spring training begins.

"It's going good," he said. "I've had no problems so far" this offseason.

Beckett and Lowell also vouched for the experience of playing in Boston, which Penny weighed heavily. He called the 2003 Marlins the closest group he has been a part of.

"They're both great guys," Penny said. "I can't wait to join them again."

He'll also be joining Kotsay, who appeared finished with the Sox after last year's valuable late-season contribution. Kotsay expressed his desire to seek a full-time position during his first offseason as a free agent, and Epstein intimated during a press conference held shortly after the season that he expected Kotsay to find an everyday role.

Kotsay, 33, batted .226 with 12 RBIs in 22 regular-season games with the Sox after arriving in a trade with the Braves Aug. 27. Kotsay took over as the starting first baseman in the postseason when Lowell was sidelined with a hip injury, necessitating the move of Kevin Youkilis to third.

With Lowell's health in question after offseason surgery, Kotsay's versatility may become just as important this season.

Epstein and his staff can now check the empty boxes next to "likely fifth starter" and "versatile, reliable bench player." With Thursday's signing of backup outfielder Rocco Baldelli and the seemingly imminent signing of pitcher John Smoltz, the Sox have only two needs left to fill, one minute and one massive: a 12th pitcher for the bullpen and a starting catcher.

The Sox also made a couple of minor moves. Righthanded minor league pitchers Virgil Vasquez and Dewon Day were claimed off waivers by the San Diego Padres and Tampa Bay Rays, respectively. The Sox' roster is now at 39.