Here are some likely candidates, based on pedigree, experience and general industry buzz -- all under the age of 40:
Current job: Assistant GM, Cleveland Indians
The latest: Antonetti interviewed for the Phillies GM job in 2005 and took his name out of the running for the Cardinals job when it opened in 2007. Antonetti, who is believed to the eventual heir to Mark Shapiro when Shapiro moves up the ladder to the role of team president, was signed to a contract extension through 2011 and has been with the Indians organization for nine years. His area of expertise lies in contract negotiations and statistical analysis.
The resume: Antonetti earned a bachelor's degree in business administration from Georgetown University and then a masters degree in sports management from the University of Massachusetts. He worked in the Minor League operations branch of the Montreal Expos until joining the Indians in 1999 at an entry-level position.
Quotable: "I am very fortunate to be in a great personal and professional situation in Cleveland. After conversations with Mark and [team president] Paul Dolan, I am very comfortable with my current position and future with the Indians." -- Antonetti, after removing himself from consideration for the St. Louis job
Current job: Senior vice president and assistant GM, Boston Red Sox
The latest: Since his co-assistant, Jed Hoyer, departed to take the GM job in San Diego, Cherington has transitioned from a role overseeing scouting and player development to a more traditional assistant GM role focusing on Major League roster construction, professional player evaluation and contract negotiations.
The resume: Cherington, a New Hampshire native, graduated from Amherst College in Massachusetts and earned a masters in sports management from the University of Massachusettes. He did advance scouting for the Cleveland Indians before joining the Red Sox, when hired by former Boston GM Dan Duquette in 1997. Cherington, along with Hoyer, served briefly as co-GMs, when Epstein vacated the position for a few months in late 2005.
Quotable: "We are enormously proud of the work that [Cherington and Hoyer] have done already in their career. They have been major contributors in a variety of different areas to the success of this club and to the success of the club on the field in particular." --Red Sox president/CEO Larry Lucchino, introducing Cherington and Hoyer as co-GMs in December 2005
Current job: Assistant GM, Oakland A's
The latest: Forst will enter his 11th season with the A's and seventh as assistant GM, a position he started in February 2004. His primary duties include assisting GM Billy Beane in all player acquisitions, contract negotiations and player evaluations.
The resume: Forst graduated cum laude from Harvard University in 1998 with a bachelor of arts in sociology and played baseball for the Crimson for four seasons, earning third team All-America honors as a senior. He also played for the Springfield (Ill.) Capitals of the independent Frontier League in 1998 and '99 before joining Beane's team alongside former A's assistant GM and Dodgers GM Paul DePodesta.
Quotable: "[Forst] was a guy who is not only passionate and smart but who had played baseball beyond the college level -- and who was passionate enough to play beyond the college level. He was clearly willing to sacrifice quite a lot for his passion." -- DePodesta to the San Francisco Chronicle in 2007
Current job: VP and assistant GM, Arizona D-backs
The latest: Woodfork assists GM Josh Byrnes in all phases of baseball operations, primarily focusing on the management of the club's 40-man roster as well as contract negotiations, scouting and Minor League player development.
The resume: Woodfork is a 1999 graduate of Harvard, where he earned a degree in psychology and started in the infield alongside Forst. After college, he worked for three years with MLB's Labor Relations department in the Commissioner's Office. While there, he worked with the baseball operations departments of all teams, assisting them with the interpretation of the Collective Bargaining Agreement, salary arbitration and advising them of upcoming deadlines. Woodfork also took part in the creation of the 2003-06 Basic Agreement between the Player's Union and MLB. He joined the Red Sox in 2003 and worked for three years as director of basball operations and assistant director of player development before following former Red Sox assistant GM Byrnes to Arizona.
Quotable: "[Woodfork] has built a tremendous reputation in this industry due to his successful track record with the Commissioner's Office and the Red Sox." -- Byrnes
Current job: Assistant GM, Seattle Mariners
The latest: Kingston joined the Mariners last September, replacing longtime assistant GM Lee Pelekoudas, and made a big impact this winter, being a key operator in the negotiations that ultimately led to the signing of staff ace Felix Hernandez to a five-year contract extension.
The resume: Kingston graduated from Dickinson College in Pennsylvania in 1999 with a degree in economics, started in baseball when hired by Epstein as an intern for the Padres, and spent the last nine seasons working his way up through the San Diego baseball operations department. Kingston was named the Padres' director of baseball operations in November 2002, a title he held until being hired by Seattle. While in San Diego, he was primarily responsible for assisting former GM Kevin Towers and assistant GM Fred Uhlman Jr. in all player acquisitions as well as roster, payroll and budget management, contract negotiations and salary arbitration efforts and overseeing statistical analysis and scouting efforts.
Quotable: "I am excited to add Jeff to our front office staff. He assisted in several capacities with San Diego, and his skill set and diversity will aid this organization as we move forward." -- Mariners GM Jack Zduriencik when Kingston was hired
Current job: Senior director of player personnel, Texas Rangers
The latest: Preller has shot up the organizational ranks and is now overseeing all scouting and has a hand in acquisitions.
The resume: Preller, who went to Cornell University with Rangers GM Jon Daniels, joined the Texas front office in November 2004 after working in baseball operations with the Los Angeles Dodgers, MLB and the Arizona Fall League. In the course of directing the club's scouting operation and acquisitions in Latin America, he uncovered much of the talent, including phenom reliever Neftali Feliz, that has pushed the Rangers' farm system to a high ranking among baseball publications.
Quotable: "He's a critical piece to what we do. He has been very involved in setting our organizational and scouting philosophy and how we evaluate and acquire players. He is one of the better evaluators in the game today. He's earned the respect of everybody in the industry in how he goes about his job." -- Daniels
Doug Miller is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.