By Larry Fine

(Reuters) - Tim Wakefield, who carved out a 19-year Major League Baseball pitching career thanks to his utterly unpredictable knuckleball, announced his retirement from the Boston Red Sox on Friday.

Wakefield, at 45 the oldest player in MLB last season, had a 200-180 career record with a 4.41 earned run average and won two World Series championships (2004, 2007) with the Red Sox.

"This has been the hardest thing I have ever had to do," an emotional Wakefield said during a news conference at Boston's Spring Training facility in Florida. "So it is with a heavy heart that I stand here today and I am saddened to say that I have decided to retire from this wonderful game of baseball."

The rubber-armed Wakefield, who played 17 seasons for Boston after two years with the Pittsburgh Pirates, is third on the Red Sox list for career wins (186), six short of the team record held by Cy Young and Roger Clemens.

Only Carl Yastrzemski (23 seasons), Ted Williams (19) and Dwight Evans (19) played more seasons with Boston than the long-lasting Wakefield.

He went 7-8 last year with 5.12 ERA and struggled down the stretch with a 6.30 ERA over his final four starts as Boston squandered what had appeared to be a sure berth in the playoffs.

Drafted by Pittsburgh in 1988 as a first baseman, Wakefield decided his odds of reaching the majors were better as a pitcher and developed the tricky knuckleball delivery to speed his progress.

The knuckleball is a pitch delivered with fingers dug into the ball in order to release it without imparting spin.

Not only is the speed of the delivery cut by about one-third, but the floating ball is affected by air conditions and currents that can drastically alter its flight.

It can be as hard for a catcher to corral as for a batter to hit.

Former major league catcher Bob Uecker, who went on to a career in broadcasting and comedy, once quipped that catching a knuckleball was easy.

"I just wait until it stops rolling and then I pick it up," said Uecker.


Armed with the beguiling pitch, Wakefield found himself on the fast-track to the majors and joined the Pirates for the 1992 season and posted an 8-1 record. But then the right-hander lost control of the pitch and was cut by Pittsburgh.

After a standout season for Boston's Triple-A minor league team, Wakefield was a hit with the Red Sox in 1995, going 16-8 with a 2.95 ERA in what might have been his best season.

Despite never quite reaching those heights again, Wakefield remained a fixture with the Red Sox and doubled as a relief pitcher over the years.

The durable hurler notched 15 saves besides starting 17 games in 1999, and had 22 saves in all during his career.

Wakefield made his only All-Star team in 2009 and was 11-5 with a 4.58 ERA in 21 starts that season.

Also known for his charitable work, Wakefield was given MLB's Roberto Clemente Award in 2010, presented to the player who best reflects the spirit of giving back to the community, for his work with charities assisting needy children.

Wakefield's retirement left R.A. Dickey of the New York Mets as the only active knuckleballer in the major leagues.

"When it came do to it I had to take a hard look at what I thought was best for me, my family and the Red Sox," he said.

"There is nothing that I want more than for this team to win and it is hard sometimes to take yourself out of the decision process, but in my heart I feel that by retiring I am giving them a better chance to do that."

(Reporting By Larry Fine in New York; Editing by Frank Pingue)