"He's one of the top left-handed relievers in the game, a guy we're really impressed with and always had difficulty hitting against," Reds general manager Walt Jocketty said of Marshall. "We felt he'd be a great addition to our club."
Jocketty said that talks about Marshall with the Cubs and baseball operations president Theo Epstein began during November's General Managers Meetings and continued some at the Winter Meetings this month. But they did not escalate until this week.
Last weekend, Jocketty executed a daring trade as he acquired starting pitcher Mat Latos from the Padres for three premium prospects in Yonder Alonso, Brad Boxberger and Yasmani Grandal along with former rotation ace Edinson Volquez.
The Reds had spent the past several seasons accumulating young talent and decided to cash some of the chips in. With the National League Central in flux as the Cardinals cope with losing Albert Pujols and the Brewers brace for losing Prince Fielder as a free agent, opportunity is knocking for Cincinnati.
"There were some areas we thought we were lacking in," Jocketty said. "The way to address it, for us, was to do it through the trade market. We're not going to go out and afford high-priced free agents. That's part of the reason we sign and develop players -- whether we use them to keep for our Major League club or use them in trades. I never like giving up young players. It's always an extremely difficult call for me to talk to these young guys when we trade them. But sometimes we feel it's necessary to do that."
Marshall, 29, has been one of baseball's best relievers, with a 2.45 ERA in 158 appearances over 2010-11, second only to Atlanta lefty Jonny Venters in that span.
Last season, while going 6-6 with a 2.26 ERA in 78 games, Marshall walked 17 and struck out 79 over 75 2/3 innings pitched. Although a native of Virginia, he had been making his home in the Chicago area.
"It came as a surprise. But I understand the moves Theo [Epstein] and the crew are making," Marshall said. "At first, it'll be a bit of an adjustment. I had my whole career here as a Cub. But I understand I've been lucky in that aspect. It's part of the game with trades and signing with different teams.
"I'm just looking forward to embracing the opportunity to go to the Reds and have a chance to really compete and win a division, and hopefully come home after the season with a World Series ring."
The Reds still have an opening for the closer's role, but Marshall will be employed for the time being as a lefty setup man along with Bill Bray and right-hander Nick Masset. Jocketty did not rule out the closer's spot for Marshall, however.
"It's a possibility," Jocketty said. "We're still talking with [free agent Francisco] Cordero. But if we don't sign or acquire a closer, we have several guys we feel can take over that role. Sean would certainly be one of them."
Marshall's ability to get hitters out from both sides of the plate makes him an attractive candidate to close. Last season, right-handers batted .249 while lefties batted .206 against him. In 2010, it was .218 for righties and .196 for lefties.
"I think some of the pitches and offspeed pitches that I throw can be effective for both," Marshall said. "I didn't have a problem last year and the previous years when [managers] Lou [Piniella] or Mike Quade put me in a situation where I'd face three righties in an inning. It didn't at all intimidate me."
Marshall recorded five saves last season when Chicago closer Carlos Marmol struggled or was unavailable.
"It was a thrill for me," Marshall said. "I enjoyed it, being able to lock the game down and seal a win for the team. I'm more than comfortable in the closer's role."
Adding more risk to the Reds' side in this deal is that Marshall can become a first-time free agent after next season. He will earn $3.1 million in 2012. Marshall underwent a physical before the trade was finalized, but there was no long-term contract extension included.
"There are no guarantees," Jocketty said. "But we're going to do our best to try and sign him. Hopefully when Sean gets to Cincinnati and sees what a great place it is to play, a great organization we have and a good ballclub, that he's going to want to stay for a while."
Following a strong rookie season in 2010, the 24-year-old Wood was a disappointment last season. He was 6-6 with a 4.84 ERA in 22 games, including 18 starts, and was twice demoted to Triple-A Louisville.
Wood became more expendable after the Latos trade and was unlikely to crack the Reds' rotation this spring.
Sappelt, who turns 25 in January, made his big league debut last season and batted .243 in 38 games with the Reds. He batted .313 in 79 games at Louisville. In 2010 at three Minor League levels, he batted a combined .342.
Only 19 years old, Torreyes batted .356 with a .398 on-base percentage in 67 games last season at Class A Dayton.
"There's no doubt our bullpen just got weaker by losing Marshall -- you can't get around that," Epstein said. "But I think our starting rotation just got stronger, and our farm system just got stronger. If Wood bounces back and he pitches the way he did in 2010, you can argue that maybe we even got better [for] 2012. Certainly, the future just got a little bit brighter."
As for the Reds, Jocketty did not rule out more moves after the holidays.
"After the first of the year, we'll take a look at some things," Jocketty said. "We still want to address our bench, maybe left field and see what we can do."