Aybar failed up to expectations in his first audition with the Cardinals, but his 10-0 record in Triple-A Memphis in 1998 earned him another chance to shine in St. Louis. Working out of the bullpen in 1999, Aybar showed improvement even though he had yet to master an effective changeup that could stop hitters from keying in on his above-average slider.
Out of options and out of chances, the converted shortstop was traded to Colorado in November as part of a seven-player deal that brought pitchers Darryl Kile and Dave Veres to St. Louis. The move kicked off a season-long tour of the National League, as subsequent deals shipped Aybar to Cincinnati in April (after just one appearance with the Rockies) and on to Florida in July.
After signing with the Chicago Cubs in the winter as a free agent, Aybar worked out of the bullpen but was little help to the team, allowing 16 runs in 22 2/3 innings. With the Cubs in the middle of a postseason run in late July 2001, Aybar was included in a deal with the Tampa Bay Devil Rays that brought bring Fred McGriff to the North Side.