The reason for the holdup is the review of medical information, which will be more comprehensive than usual because of Lowell's surgically repaired hip.
According to The Boston Globe, the sides have agreed on the amount of cash the Red Sox will transfer to the Rangers to account for Lowell's $12 million salary in 2010. Reported estimates are that Boston would send $8 to $9 million to Texas, but the exact amount has yet to be reported or confirmed. The trade -- as in any acquisition that includes the transfer of cash -- will have to be approved by Commissioner Bud Selig.
The Red Sox are also taking a look at Ramirez's medical files, as he had some wrist issues in 2009.
"Both clubs understand where the other one is and what we're looking to do," said Rangers general manager Jon Daniels on Thursday, before departing the Winter Meetings. "I'll just say that the general parameters of the deal are relatively understood. Both clubs know what's on the table, and we'll continue to talk here and work through it."
Red Sox general manager Theo Epstein departed Indianapolis on Thursday morning and was unavailable for comment.
Lowell, 35, had right hip surgery at the end of the 2008 season. Ever since that procedure 14 months ago, doctors have told Lowell and the Red Sox that his mobility would be better in 2010 than in '09, as he would have more time to recover.
If the Red Sox -- as expected -- move on from Lowell, their third baseman of the past four seasons, they are expected to make a run at free agent Adrian Beltre, an elite defender who is coming off a down year at the plate.
Ramirez, 25, has played 17 games in the Majors, all in 2008. He has played in 507 Minor League games, hitting .269 with 69 homers, 329 RBIs and a .398 on-base percentage.
The Red Sox have Victor Martinez and Jason Varitek lined up as their catchers for 2010, but Ramirez could provide them depth for the coming season, as well as an option for a Major League spot down the line.
As of Wednesday evening, the Boston Herald characterized Boston's interest in Beltre as "significant."
Scott Boras, who represents Beltre, said he has spoken with several teams during the Winter Meetings about the two-time Gold Glove Award winner.
"I think teams are looking for offense -- they're looking for complete players," Boras said. "I think in infield play that there are certain third basemen that clubs want to move or transfer from another position, and that creates opportunities for Adrian. We've had probably five or six teams that have expressed interest in him."
Epstein said that his club did converse with Boras at the Winter Meetings, but he didn't elaborate on the subject matter.
The 30-year-old Beltre hit .265 with just eight homers and 44 RBIs in 2009, his season shortened by six weeks because of left shoulder surgery.
In the three seasons before that, Beltre averaged 25 homers and 88 RBIs, while playing half of his games at Safeco Field, hardly a hitting haven. It would stand to reason that his offense would have some type of resurgence at Fenway, particularly because Beltre -- a right-handed hitter -- pulls the ball most of the time. Beltre has expressed interest in returning to the Mariners, and Seattle is keeping that option open, despite the recent signing of Chone Figgins. The Mariners have said that Figgins could switch positions if Beltre returns.
"I don't think anyone in baseball will not tell you Adrian Beltre is far and above the best defensive third baseman in the game," Boras said.
But Beltre is far from Boston's only option should the Lowell trade get finalized.
Thanks to the versatility of Kevin Youkilis, who can play either corner spot, the Red Sox could instead acquire a first baseman. Free agent Nick Johnson, known for his on-base skills and slick glove, is a player the Red Sox have long liked. Adam LaRoche, who spent just over a week with the Red Sox last July, is another free agent. Mark DeRosa is a right-handed bat who can play the corner infield and outfield positions, as well as some second base.
Lowell has been a steady contributor at the plate throughout his time in Boston, not to mention a highly respected figure in the clubhouse and a popular player among the fans.
His most memorable season in Boston was 2007, when he helped the Red Sox win a World Series championship, hitting .324 with 21 homers and 120 RBIs. Lowell was the Most Valuable Player of the '07 World Series sweep over the Rockies. At the championship parade, Red Sox fans continually shouted to "Re-sign Lowell." They did, for three years. But it appears that Lowell's time in Boston could end with a year left on that contract.
Thanks to right hip woes in 2008 and the recovery from surgery that followed last season, his range has decreased from what it once was. Lowell will be 36 years old on Opening Day. If Lowell goes to the Rangers, he will likely split his time between first base and designated hitter. Texas has Michael Young at third base.
Epstein has said several times this season that one area that he'd like to upgrade from the 2009 team is defense. Beltre over Lowell would be an upgrade. In recent years, Lowell has been a more productive hitter than Beltre. And if the Sox move Youkilis to third and get a plus defender to play first, that would be another way to conceivably upgrade defensively.
Boston now feels good about its defense at shortstop with the addition of Marco Scutaro. It remains to be seen how much more Epstein will do to tighten up on defense. Like everything else, it is a balancing act.
"I think we could do more, certainly," said Epstein on Wednesday. "Whether we're able to or not remains to be seen. I think it will be hard to improve both on offense and with our defense, but I'm not sure which direction it will go yet."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.