Lake Buena Vista, Fla. — Because the Braves' bullpen was overcrowded and his performance was underwhelming, Tyler Yates knew it could be a bad day. Especially when he entered the clubhouse Wednesday and pitching coach Roger McDowell approached.

"I walked in and Roger said, 'We need to talk to you,' " Yates said. "I thought, 'Oh, God.' "

The Braves traded Yates to Pittsburgh for minor-league pitcher Todd Redmond, a 22-year-old right-hander who will begin the season in Class AA Mississippi's rotation.

"With this move and one more, we will be in position where our roster is manageable before opening day," said general manager Frank Wren, adding that the Braves would make one or two more trades by Saturday, when the 25-man opening day roster must be set.

The Braves are seeking a bench player with more experience and power than they have now.

Catcher Brayan Pena and first baseman Scott Thorman are out of minor-league options, meaning they would have to clear waivers before they could be sent to the minor leagues.

Switch-hitting Pena has drawn more trade interest, and with the shortage of catchers around baseball he would be quickly claimed by another team if the Braves tried to get him through waivers.

By trading Yates, who had a 5.18 ERA in a career-high 75 appearances in 2007, the Braves reduced to three the group of out-of-options relief pitchers competing for the last two or three bullpen jobs.

"I was hoping to be in Atlanta," said Yates, a Hawaii native. "But looking at the way the spring has gone, I prepared myself. I told my wife and my dad to be prepared, something could happen.

"I love Atlanta, love the guys on the team. My wife and I even bought a house in North Atlanta. But [being traded] is part of the business."

Hard throwers Blaine Boyer and Chris Resop and left-hander Royce Ring are out of options, and the Braves seem inclined to keep them on the 25-man opening day roster. All pitched well this spring, while Yates had a 9.00 ERA and nine walks in eight innings.

"We were in a predicament," manager Bobby Cox said. "All good arms out there; you hate losing anybody. We got a nice prospect [in return for Yates]."

Redmond is 22-21 with a 3.27 ERA in three seasons in the low minors, with 318 strikeouts and 89 walks in 393 innings. He was rated the No. 27 prospect in the Pirates' organization.

Yates' performance in 2007 was a tale of two seasons. He was 2-0 with a 3.06 ERA and stingy .183 opponents' average in 37 appearances through June, and 0-3 with a 7.63 ERA and .318 opponents' average in 38 appearances the rest of the season.

"It's tough to see a friend go," reliever Peter Moylan said. "But it's just the nature of the business. We had so many guys out of options, so many guys throwing well."

The four certainties for the seven-man bullpen are closer Rafael Soriano, Manny Acosta, lefty Will Ohman and Moylan. With John Smoltz (sore shoulder) to open the season on the disabled list, the Braves could use his roster spot to carry an extra pitcher. "It does give us a little more flexibility," Wren said.

Jeff Bennett has pitched splendidly in his past four games (four hits in 11 scoreless innings) and could win a job as a long reliever/spot starter.