O'Connor went 3-8 with a 4.80 ERA in 21 games, including 20 starts, in 2006, but he often pitched well despite losing his last five decisions and not winning after early June.
A sore elbow sidelined him from late July to early September, and O'Connor had arthroscopic surgery in November.
Like Acta, O'Connor said his return will take time.
"I don't know how long it's going to take for me to get on the mound and how long, from there, it's going to take me to get into a game," O'Connor said. "So it's hard to say when, for sure, I'll be back. I've never had any arm injuries, so it's all new to me."
O'Connor made it clear he will not rush getting back because he wants his elbow to be normal once more.
"The whole point of this is when I'm done with it, to be 100 percent and not have to deal with this anymore this season," O'Connor said, "or any time after that, really."
Washington's pitchers and catchers report to Spring Training in Viera, Fla., on Feb. 13.
No Ohka for Nationals: Contrary to published reports, the Nationals are not in the final three in terms of acquiring pitcher Tomo Ohka, according to a baseball source.
Ohka wants more money than the Nationals are willing to give, so Washington won't be going after him. Jim Masteralexis, Ohka's agent, told MLB.com last month the Nationals offered Ohka a contract below market value.
Washington traded Ohka to Milwaukee during the 2005 season. He had an 11-11 record with a 4.55 ERA in 40 games for the Brewers in 2005 and 2006.
In addition, Ohka was out from May 2-July 17 last season because of a right rotator cuff condition. He didn't need surgery, but he sat out the final two weeks of the year after straining his right hamstring running the bases against the Nationals.
Ohka pitched for Montreal/Washington for over three seasons. His best year came in 2002, when he went 13-8 with a 3.18 ERA.