The Cardinals assigned Lambert to the Single-A Peoria Chiefs in the Midwest League and began playing immediately, posting a 1–1 record with an ERA of 2.38 in nine starts. Promoted to the Single-A Palm Beach Cardinals for the 2005 season he continued to dominate, going 7–1 with a 2.63 ERA in ten starts and earning a quick promotion to the Double-A Springfield Cardinals in the Texas League. The transition to Double-A baseball proved difficult; Lambert went 3–8 with a 6.35 ERA. In an interview, Lambert admitted that he "hadn't pitched that well, yet." A bright spot came at the end of the year when he was named to the United States national baseball team. Lambert returned to Double-A for the 2006 season and showed improvement, posting a winning record and a lowered ERA of 5.30. Lambert made a single appearance at the end of the season with the Triple-A Memphis Redbirds, but was tagged for a loss, giving up three runs in four innings. After stints in spring training and minor league camp to open the 2007 season, Lambert was back in Springfield again. After a strong start, however, the Cardinals promoted him to Memphis, this time for good. However, for the first time, Lambert would be working out of the bullpen: after years in the minors, he was no longer the power pitcher he had been in college. Lambert was philosophical about the change: "I guess that's just the way they thought I'd get to the big leagues. I've had my good innings and bad innings." Lambert would not, however, reach the majors with the Cardinals; on August 30, 2007, he was traded to the Detroit Tigers as the player to be named later to complete the deal which sent pitcher Mike Maroth to the Cardinals. The Tigers assigned Lambert to the Toledo Mud Hens, their Triple-A club.
Detroit Tigers
Lambert's time as a relief pitcher for Memphis had not been a success: in 28 appearances he was 1–4 with an ERA of 7.49. The Tigers, accordingly, returned Lambert to a starting role. He made one start at the tail end of the 2007 season; a six-inning performance in which he allowed just one hit while striking out ten. The Tigers invited Lambert to 2008 spring training, but he did not make the major league cut and returned to Toledo, where he went 5–3 with an ERA of 3.37 in his first 12 starts. On August 23, the Tigers announced their intention to recall Lambert to start on the 26th in place of the struggling Nate Robertson. Lambert made his first major league debut for the Tigers on August 26, against the Cleveland Indians. He struck out the first batter he faced, Indians outfielderGrady Sizemore, but would end up going 2-1, with an ERA of 5.66 to finish out the year. Lambert was designated for assignment August 18, 2009.
Baltimore Orioles
Lambert was claimed off waivers by Baltimore August 20, 2009. He would appear in four major-league games with Baltimore at the end of that season, pitching a total of 5 2/3 innings, all in relief. His contract was not renewed for the following season, and he did not return to the minor leagues, so that his professional baseball career ended after 2009.