DENVER -- One of the Giants' best bullpen arms, Santiago Casilla, could return to the mound relatively soon after throwing two simulated innings against live batters at Coors Field on Friday.
Casilla had surgery to remove a cyst from his knee in late May, and the right-hander said he felt about 75 percent during the pitching session.
"We never feel 100 percent," Casilla said with a smile.
Manager Bruce Bochy said it's unlikely the shutdown reliever, who has boasted a 1.89 ERA in 21 appearances (19 innings), will be activated on the Giants' current road trip.
But Bochy was pleased with the progress he saw from Casilla today and will soon make a decision on the next step of the rehab process. Casilla last pitched May 20 and had not allowed a run in his last six appearances.
"Felt good, we'll see how he comes out of it," Bochy said. "We'll make a decision tomorrow morning for him on what the next move is. But possibly could be starting rehab real soon."
Healing Arias available as pinch-hitter vs. Rox
DENVER -- After missing two games, Giants infielder Joaquin Arias was available as a pinch-hitter in the series opener against the Rockies Friday.
Arias injured his hamstring running the basepaths against the Dodgers on Monday, but said he felt better and would be available on Friday. Arias tested the hamstring with light pregame jogging at Coors Field and manager Bruce Bochy confirmed he will be available off the bench.
"[Fans] could possibly see him pinch-hit," Bochy said. "That would be his duty today. We're going to limit him today.
"He did come out early, he swung the bat, fine swinging, ran a little bit. So he's available."
There was genuine concern that Arias would have to go on the disabled list, but Bochy said that option is not as likely.
"His progress has been about what [Giants athletic trainer] Dave Groeschner told us," Bochy said. "So I am a bit more optimistic that he's coming around."
The versatile Arias, who has played at least five games at first base, third base and shortstop, is batting .276 with 10 RBIs and 29 hits in 58 games.
Bochy reflects on close race in NL West
DENVER -- Almost exactly halfway through the season, the National League West remains a bundle of uncertainty, with all five teams within six games of each other going into Friday night.
The Giants head into the first of a three-game series with the Rockies tied for third place, both teams four games back of the D-backs. At 42-36 entering Friday, Arizona is the lone team in the division over .500, granting the four other teams a second life in the race for the NL West crown.
"It's not what I quite thought in one way, that there would be one team over .500," manager Bruce Bochy said. "But I did think it would be somewhat of a tight race with all the teams involved, and that's what it is. Some of us are fortunate that it's a tight race at this point, particularly us. We've had our own struggles.
"I think it should be this way all year."
San Francisco has dropped seven of its last eight and nine of 12, sitting two games under .500 this late in the season for the first time since 2008. The Giants finished 72-90 that year, fourth in the division.
• Bochy doesn't expect starter Eric Surkamp to join the rotation in the near future. Surkamp has not pitched this year after undergoing offseason surgery on his pitching elbow. They lost another starter when Ryan Vogelsong broke his right hand May 20.
Though injuries have partially dismantled one of the best rotations in the Majors, Bochy isn't feeling sorry for himself and has been impressed with the work of lefty replacement Mike Kickham.
"It's always a challenge when you lose a starter," he said. "The players out on the field, I've always said they're a little easier to replace than pitchers or even somebody in the bullpen because you do have to juggle a little bit.
"But it's part of the game. You have to deal with it. We're not the only club with injuries, we know it. So we just try to focus forward and that's our approach."
• Bochy said he talked to Friday's starter, Barry Zito, and Tim Lincecum after both struggled in back-to-back starts in Pittsburgh earlier this month.
"We need [Zito] to be more consistent on the road, he and Timmy both," the Giants skipper said. "I think Timmy has been and Zito has been in the past."
Ian McCue is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.