Greene, on the DL since May 29 with anxiety issues, was hitting .200 with two home runs and 14 RBIs in 38 games before seeking treatment for social anxiety disorder.
"I don't want to be watching from the sidelines," Greene said. "I came here to try and contribute to the team in whatever way possible. If that's shortstop or third base or coming of the bench, whatever I need to do, I'm ready to do it."
Greene, who has missed 19 games, hit .400 during a short four-game rehab stint in Memphis in which he played shortstop and third base. He was not in manager Tony La Russa's lineup for Thursday's game, but figures to see significant playing time at both positions.
"I plan to play him," La Russa said. "He's not playing today and today's the day we are talking about, but he'll play."
The Cardinals made another roster move on Thursday, recalling pitcher Josh Kinney and optioning pitcher P.J. Walters to Memphis. Kinney, who began the season with the Cardinals before being sent to Memphis on April 17, was 1-1 with a 3.12 ERA in 21 relief appearances for Memphis.
"We've got two innings guys in Walters and [Blake] Hawksworth and we only need one," La Russa said of the move. "Kinney fits us better. Also, it lets P.J. go down there and keep pitching. He needs innings."
Stavinoha was hitting .234 with one home run and 13 RBIs before being sent down. The Cardinals could have kept Stavinoha and sent out another pitcher, but instead wanted to stay with the unbalanced 13 pitchers and 12 position players on the roster.
"It's a tough call, but it gives us a lot of versatility with the guys that are here," La Russa said. "All of those guys can play different positions. You can't have everything."
B.J. Rains is an associate reporter for MLB.com This story was not subject to the approval of Major League Baseball or its clubs.