Kotsay hit .289 with six home runs and 37 RBIs in 88 games with the Braves. He arrived at Yankee Stadium on Wednesday before Boston's game against New York and was available off the bench.
"I figured once I cleared waivers and there wasn't really any action that I'd finish out the season in Atlanta," Kotsay told a pool reporter. "But this obviously is exciting to come to a club that's in the playoff race, and especially one like Boston that has the history of a great tradition."
Kotsay's only postseason experience came in 2006 with Oakland. The Red Sox lead the AL wild-card race and began the day 3½ games behind first-place Tampa Bay in the AL East.
"It's very invigorating, no question," Kotsay said. "Unfortunately in Atlanta, things didn't go as well as we would have liked. I see Atlanta giving me this opportunity and we have to be thankful for that as well."
A strong defensive player, Kotsay has primarily played center field since 2001, when he joined the San Diego Padres. Before that, he was a regular in right field for Florida. He's also played 28 major league games at first base and could see time there with Boston.
Red Sox manager Terry Francona said he'd have to talk to Kotsay before determining his role.
"He's going to play. He's going to help us," Francona said. "The one thing I've heard from numerous people is, if he can walk he'll play."
The 32-year-old Kotsay, like Drew, has been hampered by back pain during his career.
"I know that I've gotten messages from people all over the league that said he's everybody's all-time favorite. I know he's a real professional. I know he's excited about coming here," Francona said. "He said he'll do anything we ask to try to help us win."
Drew, an All-Star right fielder, was placed on the 15-day disabled list Tuesday because of a lower back strain.
With Drew already ailing, Braves general manager Frank Wren said Boston GM Theo Epstein called him last weekend and it took about four days to complete the deal.
"J.D.'s injury necessitated this trade," Epstein said, then praised Kotsay. "He adds a lot to our club. He's a plus defensively in center and in right. He plays first base. He has great instincts. He's really a gamer. He's the type you want up in a big spot. ... He'll help this club on the field and in the clubhouse."
Kotsay was scratched from Atlanta's starting lineup Tuesday night, raising speculation that a trade was pending. He walked as a pinch hitter in the ninth inning.
"I'd have to say it's my weirdest night as a professional in the big leagues," Kotsay said after the game. "I've never been scratched for that type of reason."
The Braves got minor league outfielder Luis Sumoza in the deal. The 20-year-old Sumoza batted .301 in 51 games for Class A Lowell of the New York-Penn League this season.
Wren said the Braves were interested in signing Sumoza a few years ago.
"So we had a lot of background on him. He has a lot of upside. That's what you strive for in a trade like this," Wren said.
Atlanta obtained Kotsay from the Athletics on Jan. 14. Coming off back surgery, he hit only .214 with one homer in 56 games for Oakland last year.
Kotsay has a .282 career batting average with 109 homers and 597 RBIs.
"He's going to be a great addition. He's one of those leader-type guys," Red Sox pitcher Josh Beckett said.
To make room for Kotsay on the roster, Boston designated infielder-outfielder Joe Thurston for assignment. Thurston was called up Tuesday from Triple-A Pawtucket.
Third baseman Mike Lowell, on the disabled list with a strained muscle on his right side, hit off a tee Wednesday and said it went well.
Beckett said he still plans to pitch Friday night against the Chicago White Sox after skipping a turn in the rotation because of numbness and tingling in his right arm.
"Just day to day. We're going to keep checking. Be smart with it," Beckett said, adding that he appreciates the Red Sox being cautious with him. "We're not talking about the end of a season, we're talking about the end of a career when you're dealing with a pitcher's arm."
The right-hander, who is 11-9 with a 4.34 ERA, said his elbow has bothered him on and off this season.
"We're just dealing with it the best way we can. I don't think we can do anything different," Beckett said.
Epstein said the Red Sox will keep a close eye on Beckett this week.
"Even though he's scheduled to pitch Friday, we are evaluating on a day-to-day basis," the GM said. "The key is not to let guys play when they're in a vulnerable state."
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