General manager Dayton Moore said the Royals have had interest in Jacobs since before July's non-waiver Trade Deadline. A deal was firmed up this week.
"We had to sit on it for a little while because we couldn't announce anything during the World Series," Moore said.
Jacobs is expected to team with slugger Jose Guillen in the middle of the Royals' lineup.
"It's safe to say that Mike Jacobs' bat will be in the lineup every day. We do have the DH, but he'll play a lot of first base as well," Moore said.
The Marlins were looking for relief help, and Nunez was 4-1 with a 2.98 ERA in 45 games last season. He was on the disabled list from May 29 to July 21 with a strained right lat. The Marlins see Nunez as a late-inning setup man or perhaps a closer candidate down the line.
Despite playing in Dolphin Stadium, tough on left-handed power hitters, Jacobs hit 14 of his 32 homers there. Kauffman Stadium, of course, is quite spacious.
"I truly believe that if you're a power hitter and you're going to hit home runs, you're going to hit home runs no matter what park you're in," Jacobs said. "Hopefully, it won't be a problem going to another big park. I don't see that it's going to be a problem, so it's really a non-issue."
The Royals have not had anyone hit more than 30 homers since Jermaine Dye had 33 in 2000. Guillen led the club this year with 20. The franchise record is Steve Balboni's 36 in 1985.
"We think Jacobs will continue to get better. It's hard to predict how many homers he'll hit, but we see him as a middle-of-the-order presence in our lineup from the left side," Moore said.
"I think we had one of the best records in baseball against left-handed pitching [36-24] and one of the worst against right-handed pitching [39-63] last year."
Last season, Jacobs had 25 of his home runs against right-handers plus a .257 average and .315 on-base percentage.
The addition of Jacobs creates an even bigger jam at first base for the Royals , who already had Ryan Shealy, Ross Gload, Billy Butler and Kila Ka'aihue lined up there.
None of them, however, have the Major League power credentials of Jacobs. In one year with the New York Mets and the last three with the Marlins, Jacobs has a total of 80 home runs, 98 doubles and 247 RBIs in 421 games. His career batting average is .262.
Obviously, the Royals' depth at first base also creates more trade opportunities for the club.
Jacobs figured he was going to be traded.
"The Marlins had a lot of guys coming up for arbitration and they were kind of wanting to re-tool for more speed, defense and pitching, so I think it was kind of inevitable," he said.
Jacobs is eligible for salary arbitration for the first time, and his salary could reach $3.5 million in 2009. He made $395,000 this season. Nunez, whose salary was $405,000, is not yet eligible for arbitration.
Jacobs was part of history for Florida in 2008. The Marlins became the first team in MLB history to have
four infielders each connect on 25 or more home runs. Shortstop Hanley Ramirez had 33, while Jacobs and second baseman Dan Uggla each finished with 32. Third baseman Jorge Cantu delivered 29.
This year, Jacobs homered once in every 14.9 at-bats, the 10th-best mark in the Major Leagues. Among first basemen, only Ryan Howard and Albert Pujols had better marks. His 32 homers were the second most by a Marlins left-handed hitter in club history, trailing only Carlos Delgado's 33 in 2005. On Thanksgiving Day after that season, Delgado was traded to the Mets in the deal that brought Jacobs to Florida.
Not picked by the Mets until the ninth round of the 1999 First-Year Player Draft, Jacobs was originally a catcher. Arm problems prompted his conversion to first base in 2005.
Nunez, 25, was obtained by Kansas City from the Pittsburgh Pirates on Dec. 16, 2004, in a trade for catcher Benito Santiago. In four seasons with the Royals, Nunez had a 9-7 record and 4.92 ERA in 106 games, including six starts.
Nunez was nearly traded away before. On June 22, 2007, the Royals arranged a swap of Nunez to the Oakland A's for outfielder Milton Bradley, but the deal was voided because Bradley had an oblique injury.
"Noonie will be difficult to replace -- a power arm from the right side and he always took the ball," Moore said. "He has the type of presence where poor outings don't affect him. He's the same every day. He has the mind-set to be a successful reliever in the game for a long time."
Jacobs seems determined to pump up his batting and on-base averages.
"I still truly believe that I'm not a .240 hitter in the big leagues. I think the power numbers are going to stay there. I think the RBI numbers will stay there, if not be higher," he said. "The biggest thing I need to work on this [upcoming] year is being more of a complete hitter, being able to go the other way more, being able to not stay in a slump quite as long. If I get 10 more hits this year, I'm hitting .270 and my on-base percentage is .320."