PHILADELPHIA -- All the reports are encouraging that Garrett Cooper will soon be able to return from the 10-day injured list.

What the Marlins are looking to see is how the 28-year-old corner outfielder/first baseman responds to playing several days in a row. Cooper has been on the injured list since March 31 with a left calf strain, and he currently is on a rehab assignment with Class A Advanced Jupiter.

“When he shows he is healthy and able to play two, three, four days in a row, then we have to make a decision,” Marlins manager Don Mattingly said. “When they think he’s ready, and think he’s sharp. Once that’s the case, he doesn’t necessarily have to prove he can play 14 days in a row to be able to be here.”

Cooper, Miami’s Opening Day right fielder, is first eligible to be reinstated on Tuesday for the two-game series against the Indians at Marlins Park.

Weighing into consideration is the health of infielder Neil Walker, who is nursing a sore left hamstring. Walker tweaked the hamstring on Thursday night at Citizens Bank Park, and is available in a pinch-hit role on Sunday.

The Marlins are off on Monday and, if Walker is fine, they will monitor his playing time this week.

Cooper is an option at first base or either corner outfield spot. But with Brian Anderson in right field right now, left field is more of an option for Cooper, where he could platoon with Curtis Granderson.

“We know Coop’s capable of being here with his bat,” Mattingly said.

Cooper has struggled to stay healthy. He’s appeared in three games this season, and is hitless in seven at-bats. In 2018, his first season with the Marlins, he dealt with a right wrist injury that limited him to 14 games. He had surgery late in the season, but established health in Spring Training on his way to making the Opening Day roster and winning the right field job.

Best use for Chen

Finding the way to best use Wei-Yin Chen remains a work in progress for the Marlins.

On Saturday, the 33-year-old left-hander tossed two scoreless innings, giving up two hits, with two strikeouts.

“Definitely, [Saturday] was encouraging,” Mattingly said.

Chen is a long-time starter, but is currently in a long-relief role. He went six days between appearances, and has appeared in seven games overall, logging 9 2/3 innings with a 13.03 ERA.

“We’re just identifying his strengths, and making sure we’re pitching to those, and using his weapons in coordination with the way his pitches set up,” Mattingly said.

As a reliever, Chen is showing that he can bounce back physically to be available, if needed.

Starting pitching has been the Marlins’ strength, and the starters have worked deep into games on many occasions. So that limits how often the left-hander is called upon.