MIAMI -- Sunday's starter is up in the air with the scheduled bullpen session for Taijuan Walker (blister) pushed back another day. That counts him out as Arizona's starter when it closes a four-game series with Miami at Marlins Park.
"It's not quite 100 percent, but it's getting better," Walker said prior to Friday's game. "It's a no-go for Sunday. We just want to be smart with it. It's still pretty early in the season, and we want to make sure it's 100-percent healthy so we don't have any setbacks."
Manager Torey Lovullo said he has a couple of options that the organization is still weighing before making a decision on a Sunday starter.
"We have a couple of candidates, nothing is imminent right now," Lovullo said. "We'll probably make that decision in the next 24 hours."
Walker said that although he's eager to get back out on the mound, playing it smart is the way to go.
"It's tough because I want to be out there pitching, but at the same time, I've got to be smart and think about the rest of the season, especially with us playing really well," said Walker, who has been playing catch and did a little flat ground on Friday. "I threw a couple of fastballs, but mostly offspeed. I threw a couple of fastballs, and it felt pretty good."
Walker said he feels "really close" to a return to the mound.
"It's just one of those things where it's got to heal on its own," Walker said. "There's no magic solution for it. But it feels like it's getting close. I would say it's probably like 90 percent."
As anticipated, nothing will be decided until Walker completes a bullpen.
"I'll throw tomorrow and then see what my options are for [a start] next week," Walker said.
Blanco sits out with jammed thumb
Gregor Blanco was not in Friday's starting lineup. The D-backs' center fielder jammed his left thumb early in Thursday's game. He came out for a defensive replacement as a precautionary measure, but he still isn't ready to play in the field.
"He's feeling good," Lovullo said. "We obviously feel like he could run the bases, so he'll be available on the bases if we need it."
Lovullo said that Blanco would go through some functional testing to see what he could do on the field to figure out what Saturday brings.

Pollock runs the bases
A.J. Pollock (strained right groin) had good days on Thursday and Friday, according to Lovullo. Working out at Salt River Fields at Talking Stick in Arizona, Pollock ran the bases but not at full speed.
"I talked to him today, and he's very encouraged by how he feels," said Lovullo, who added that Pollock would continue to do baseball activities in his process back.