CLEARWATER, Fla. -- The sirens have not sounded, but there is reason to be concerned.
Injuries to Roy Halladay, Kyle Kendrick, John Lannan and Jonathan Pettibone last season left the Phillies with a patchwork rotation that included Tyler Cloyd, Zach Miner and an inexperienced Ethan Martin. If the Phillies plan to return to the postseason for the first time since 2011, they will need to better handle injuries to their rotation.
They tried to upgrade their starting pitching depth in recent months when they signed A.J. Burnett and Roberto Hernandez, but early in camp, shoulder problems with Cole Hamels, Pettibone and Martin have left them short.
It is not an issue yet, but big league teams averaged 10.3 starting pitchers last season. Clearly, the Phillies will need more than just Cliff Lee, Hamels, Burnett, Kendrick and Hernandez to get through 162 games.
"We're always concerned about the starting pitching depth," Phillies general manager Ruben Amaro Jr. said before Friday's Grapefruit League game against the Tigers at Bright House Field. "We have to be. You can never have enough pitching."
Everybody in camp seems to believe Hamels will miss no more than a couple of starts in April. He felt some discomfort in his left shoulder in November, and is a little less than two weeks behind schedule. He threw his first bullpen session Wednesday. Pettibone threw a bullpen session Friday after receiving a cortisone injection in his right shoulder Feb. 17. He said he hopes he can be ready sometime in early April.
Martin received an MRI exam Friday after he experienced discomfort in the back of his right shoulder Thursday.
His fastball averaged 93.2 mph last season. It hit just 85 mph Thursday.
The common theme with Hamels, Pettibone and Martin is the shoulder. Halladay, Kendrick, Mike Adams and Mike Stutes also had shoulder injuries last season.
Halladay and Adams required surgery.
Amaro said he sees no connection to the injuries. They are just a coincidence.
"I love our medical team," Amaro said. "They know what they're doing. They are good at stretching the shoulder. They're state of the art with the things they do with the guys. There's no common denominator here. It's anatomy."
Because of scheduled days off early in the 2014 schedule, the Phillies will not need a fifth starter until April 14, which is 13 games into the season. But who do the Phillies have to step in, if needed?
Miguel Alfredo Gonzalez signed a three-year, $12 million contract last season, but he has not pitched competitively in years. He will make his Grapefruit League debut Saturday afternoon against the Yankees in Tampa (1:05 p.m. ET, live on MLB.TV).
The Phillies have tempered expectations for him in recent months.
"Of course I'm interested in seeing him," Amaro said. "It'll be an interesting test for him to see how he handles it."
B.J. Rosenberg has started in the past, so he is an option. But he excelled in the bullpen late last season, and the Phillies would like to keep him there.
"I don't know if [starting] is his best role, but if that's something we can morph him into or at least prepare him for, there's no reason not to," Amaro said.
The Phillies also have non-roster invitees Sean O'Sullivan, Jeff Manship and David Buchanan in camp. Jesse Biddle is the organization's top pitching prospect, but the Phillies have been intent on having him open the season in Triple-A.
If Hamels returns in early April, Pettibone builds off Friday's bullpen session and Friday's MRI on Martin comes back clean, there might not be anything to worry about. But the first couple of weeks of camp have shown the Phillies once again how tenuous pitching depth can be.
They just hope they don't have to relive 2013 again.
Todd Zolecki is a reporter for MLB.com.