Zack Greinke, who is coveted by multiple teams, is also high on Texas' list. There could be others worth considering as the Trade Deadline approaches and general manager Jon Daniels continues to work the phones.
"Everybody is trying to get better, we're no different than anybody else," Rangers manager Ron Washington said. "We're trying to get better. At this time of the year, if there is something to get done, J.D. will get it done."
The Rangers' need for a starting pitcher grew after it was discovered that Lewis would miss nine to 12 months because of a torn flexor tendon. But they aren't trying to fill a hole in the rotation or acquire somebody who can pitch innings. The Rangers have those pitchers in abundance.
Lewis emerged as the leader in a rotation that is heavy on physical talent and light on experience. Lewis' fastball averaged 87.9 mph, the slowest of any Rangers starter this season. But he threw it for a strike 68.4 percent of the time, the highest ratio among starters. He also led all Texas starters with 1.2 walks per nine innings, 10.2 baserunners per nine innings and 6.64 strikeouts per walk.
Lewis is also 4-1 with a 2.34 ERA in eight postseason starts. On a team that aspires much higher than just winning a division title, there is a premium being placed on pitchers who can perform at a high level in a pennant race and the postseason.
"It's frustrating to lose Colby," pitcher Derek Holland said. "He's a big-game pitcher. We're going to miss him."
Acquiring Greinke would fill that void. But the competition is fierce and there's no guarantee that will get done. The possibility exists the Rangers will have to go with what they have right now, or possibly get a boost when Neftali Feliz comes off the disabled list in early August.
"Then you go out and do the best you can," Washington said. "If that's what we have, that's what will go to war with."
If Texas is unable to acquire a "difference-maker," it still has a veteran presence in the rotation who understands what it takes to pitch in a pennant race and to be successful in the postseason. It has a pitcher who could emerge as the rotation leader.
Roy Oswalt has started 331 games in his 12-year Major League career. He has won 162 games, including 20 wins twice, in 2004-05, and is 5-2 with a 3.73 ERA in 13 postseason appearances, including 11 starts.
"I know I can be that leader," Oswalt said. "I've been around long enough and I've been around some pretty good pitchers. I know my time is limited in this game, and I'd love to pass along what I've learned and what I've seen. I've talked with Derek a lot already and I've talked with Yu Darvish a lot, just trying to relate as much information as possible."
The list of Oswalt's past teammates includes Andy Pettitte and Roger Clemens with the Astros and Lee, Hamels and Roy Halladay with the Phillies.
"A lot of it is trying to keep five guys together as a team within a team," Oswalt said. "Bring everybody together and pulling together in the same direction. Take it a start at a time ... a lot of guys try to get too far out front and looking down the road rather than focusing at the task."
Lee gave the Rangers that boost of leadership in 2010, when he was acquired from the Mariners on July 9. But he was already pitching well and had already been selected to the American League All-Star team when the trade went down.
Oswalt is still trying to re-establish himself. He was a free agent this offseason, but did not sign with Texas until late May. He had to make four starts in the Minors before being called up to the Rangers on June 22. He is 3-1 with a 5.22 ERA in five starts, including 1-0 with a 1.50 ERA in his last two starts. Oswalt was forced to skip a start because of tightness in his lower back, but is scheduled to pitch on Sunday against the White Sox.
Texas doesn't need him to overpower the opposition. It has Holland, Darvish and Matt Harrison, and all three can hit 94-96 mph. The Rangers can pull Alexi Ogando out of the bullpen, stick him in the rotation and have a starter who throws 96-98 mph. Feliz can do the same once he is off the disabled list in early August. Oswalt really never was that kind of a pitcher.
"What he has is knowledge, and there is no substitute for know-how," Washington said. "That's what these young guys have to get ... to know how and to figure out how, because sometimes things are not always going to go in your favor."
That's what Lewis brought to the Rangers. They are not trying to fill a pitching void as much as a leadership void.