The Nationals had five roster spots open prior to Tuesday.
Mock, a right-hander who came from the Diamondbacks in the Livan Hernandez trade, spent most of his time with Double-A Harrisburg this past season. He was 1-5 with a 5.79 ERA with the Senators.
Jones, a boyhood friend of Ryan Zimmerman, spent time with the Gulf Coast Nationals, Class A Potomac and Harrisburg. His best work came with Potomac, where he went 7-8 with a respectable 3.96 ERA in 17 games.
Whitesell has been in the Nationals' organization since 2003 and ended up having his best season in 2007, hitting .284 with a career high 21 home runs and 74 RBIs for Double-A Harrisburg.
Bernadina, who played a few games with the Major League club during Spring Training, spent time with Harrisburg and Triple-A Columbus and hit a combined .259 with six home runs and 37 RBIs.
Trade talk: The Nationals are in trade talks on a daily basis, but one guy who is not on their list to acquire is Red Sox center fielder Coco Crisp. While he is a very good center fielder, Crisp has a career .329 on-base percentage, which is not appealing to the Nationals.
Crisp, who was in a slump during the American League Championship Series against the Indians, found himself on the bench for Games 6 and 7. The Red Sox played Jacoby Ellsbury in those two games instead.
The Nationals are looking for a middle-of-the-order bat and a leadoff hitter for the long haul.
Maxwell house: For now, the Nationals don't see Justin Maxwell as the starting center fielder next year, but, according to general manager Jim Bowden, he will compete for the job in Spring Training.
"We project him to be in Double-A, but we are open [to anything]. This a very young talented player with great makeup," Bowden said. "I'm always open to competition. We didn't expect Ryan Zimmerman to be in the big leagues this quickly."
Maxwell is currently playing in the Arizona Fall League and is hitting .190 (8-for-42) with a home run and three RBIs entering Wednesday's action, but he looked impressive during a short stint with the Nationals last month.
Bench player: Bowden indicated that he wanted Tony Batista back with the Nationals. Batista was outrighted to Columbus, but choose to become a free agent instead.
Batista was a pleasant surprise off the bench, leading the Nationals in pinch hits and RBIs.
"Tony knows we want him back here. He did a great job off the bench. We'll see how it plays out," Bowden said. "He knows this is a good fit for him. He liked playing for Manny Acta. He likes D.C. I hope that he comes back."
Fixing the parking problem: The Nationals announced that all season-ticket holders will be offered parking for games at Nationals Park. Fans purchasing season-ticket packages, including full-season, half-season and partial-game plans, will be able to purchase parking in the area surrounding the new ballpark.
Available surface parking spaces and/or garages are currently being designated, and the process is an ongoing one.
For fans without season tickets who choose to drive to Nationals Park, or season-ticket holders who choose not to purchase parking, there will be free parking at Robert F. Kennedy Stadium with free roundtrip shuttle service to the games.
"We are very excited to announce that, due to the hard work of many, many people, we now feel confident that we will be able to provide parking spaces for purchase by any season ticket customer account," team president Stan Kasten said in a statement. "We understand there has been a great deal of concern and speculation regarding parking availability at the new Nationals Park for 2008."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.