Jay suffered the sprain on April 19, when he ran into the center-field wall. He remained out of the starting lineup for six games, while letting the bruise heal, and received a cortisone injection to assist in the healing process. He returned on April 27, but admitted on Tuesday that, even then, his shoulder never was 100 percent right.
"I still felt it," Jay said. "It was just one of those things where I wanted to be out there and try as best I could. It's gotten to the point where it's better to take a step back now, get some rest and then go from there."
The last week was a turning point for Jay, who said the discomfort began to increase during the team's recent road trip. It primarily affected Jay's ability to follow through on his swing, and that has led to a recent dip in production.
Jay hit .400 in his first 12 games back after his initial period of rest. Nineteen of those 20 hits, though, were singles, a sign that Jay's shoulder was preventing him from getting much power in his swing.
In his last 12 at-bats, Jay recorded only one hit.
"It's one of those things where I want to be out there, but if I'm not helping the team the way that I can contribute, then it's tough," said Jay, who has never previously been on the DL. "It got to the point where I'm not helping the team."
The Cardinals called up Shane Robinson to take Jay's roster spot, though the majority of center-field playing time is likely to fall on the shoulders of Skip Schumaker during Jay's absence. Carlos Beltran can also play the position, but the Cardinals might be more hesitant to move him from right field now that Beltran is dealing with a sore right knee.
There are no immediate plans for Jay to have another magnetic resonance imaging test. The MRI he had on his shoulder in April revealed no structural damage. Jay will not travel with the team during the next road trip.