CLEARWATER, Fla.

- Today, the Phillies will complete their third trip through the rotation of the spring when Cole Hamels takes the mound against the Orioles.

Absent for all but one of those trips has been the guy who projects to open the season as the No. 2 starter. Yesterday, Ryne Sandberg downplayed any concern about Aaron Harang's balky back affecting his availability for Opening Day. The manager said that the veteran righthander has more than enough time to get his body ready for the rigors of a 32-start season.

"I think he has plenty of time," Sandberg said. "He's a durable guy. His arm is in shape and he's got the outings under his belt. He's a veteran guy with a solid arm. At this point, I don't see that being a concern."

Yet with 3 weeks to go before Opening Day, the composition of the rotation beyond Hamels has emerged as a major concern. That's not to say that it wasn't a concern heading into the spring. The Phillies knew they would be without Chad Billingsley for the first month of the season as he worked his way back from surgery on his right elbow, and they knew that Cliff Lee's left elbow still presented some unanswered questions. But with Lee now expected to miss the season, the Phillies will need to lean on journeyman longman/spot starter Jerome Williams and second-year righthander David Buchanan for the duration.

They also need to find a pitcher who can fill in for Billingsley until he is ready to rejoin the rotation. The veteran righthander faced hitters in live batting practice yesterday, his second session of the spring. He is scheduled to continue facing hitters once every 5 days until he is ready for game action, which could potentially occur before the team breaks camp.

Setting aside the question marks that already existed for a pitcher who has made just two starts since 2012, Billigsley's potential replacements are an uninspiring lot.

The Phillies tapped former Astros starter Paul Clemens to take Harang's place against the Yankees on Saturday, while Sean O'Sullivan got the start yesterday against the Yankees, allowing one run and one walk with two hits and two strikeouts in three innings.

Clemens has walked six batters with only one strikeout in 6 1/3 innings this spring. O'Sullivan has allowed five runs with one walk and six strikeouts in 6 2/3 innings.

Righthander Kevin Slowey had a solid season as a spot starter for the Marlins in 2013 (4.11 ERA, 7.4 K/9, 1.8 BB/9, 1.2 HR/9 in 14 starts and six relief appearances) but the Phillies have used him out of the bullpen in his last two appearances, including yesterday's split-squad loss to the Yankees, when he allowed a pair of runs in 1 2/3 innings.

The Phillies would love for Miguel Alfredo Gonzalez to give them a reason to enter the season with him in the rotation, but the Cuban righthander remains a mystery. In yesterday's split-squad game against the Red Sox, he allowed a loud leadoff double to Jemile Weeks and then a two-run homer to Daniel Nava, both on fastballs. In his next two innings, he allowed just one baserunner.

"He made a good adjustment the second and third inning," Sandberg said. "I thought he was more aggressive attacking the zone. His pace was better . . . It just took him a long time to get on the same page with [Carlos Ruiz] and after that I thought he had a whole different demeanor about him and a whole different strategy of attacking the guys. The second and third inning he threw much better."

Gonzalez looks much better than he did last year when he showed up to camp looking nothing like a pitcher who deserved a 3-year, $12 million contract. The Phillies insist they are impressed with the way the ball is coming out of his hand. But at some point, results matter, and in three games this season Gonzalez has allowed seven runs and three home runs in seven innings while striking out five.

"I think he's showing health and he's showing some progress, mixing up his pitches," Sandberg said. "He's making progress."

Remember, these are the candidates for a spot in the rotation that is already open (at least for a month). If Harang was forced to miss time, the Phillies would open the season with two of these players pitching behind Hamels, Williams, and Buchanan.

Neither Harang nor Sandberg seems to think that is likely. Harang has consistently downplayed the severity of his back condition. The team said it was a "precautionary measure" to scratch him from his start yesterday.

He is tentatively scheduled to throw a bullpen session today. If that happens, he could be back on the mound in a game Thursday, which would give him more than enough time to start four more games and then start the second game of the regular season.

On Twitter: @ByDavidMurphy

Blog: ph.ly/HighCheese