The left-hander will have one last minor league spring training tuneup Monday in Fort Myers, Florida. If it goes well, Pomeranz could be reinstated to the roster in time to start the season's sixth game, April 9 in Detroit, according to Red Sox manager John Farrell.
Putting Pomeranz on the DL allows the Red Sox to add a player to their roster for the first five games. They likely will carry an eighth reliever from a pool of candidates that includes Ben Taylor, Chandler Shepherd, Austin Maddox or Jamie Callahan, none of whom is presently on the 40-man roster.
"It's become more and more clear to us that he's not ready to begin the season," Farrell said of Pomeranz before the Red Sox faced the Washington Nationals in their Florida spring training finale.
Pomeranz, 28, eased into spring training because of an offseason stem-cell injection. He left a March 19 start with tightness in his pitching arm.
His health has been a primary topic of conversation ever since the Red Sox acquired him in a trade last July.
A Major League Baseball investigation revealed the San Diego Padres weren't forthcoming in their release of Pomeranz's medical information before sending him to Boston for touted pitching prospect Anderson Espinoza. The Red Sox were given an opportunity to rescind the trade, but they elected to keep Pomeranz, believing they wouldn't be able to win the AL East without him.
Pomeranz went 3-5 with a 4.59 ERA in 14 games (13 starts) for the Red Sox. He dealt with forearm tightness late in the season but was able to pitch through it.
After the season, Pomeranz received the stem-cell injection to relieve his discomfort; the procedure is an alternative to the platelet-rich plasma injection that is more commonly administered to pitchers. Pomeranz described the procedure as "pretty painful."
"The way they do it is they kind of scrape the tendon, the flexor, to create some bleeding, and then they shoot the stem cells on top," Pomeranz said recently. "I was fine five minutes into it. Then, about 20 minutes later, I couldn't bend my arm for like five days."
Although Pomeranz said he could have gone at a normal pace when spring training began, the Red Sox took a more deliberate approach. He didn't make his first Grapefruit League start until March 14 and has not yet thrown more than four innings in any appearance.
"Knowing that he was coming in a little bit behind because of the procedure, and then the day that he was shortened somewhat by the triceps issue -- he's not ready to begin the season right now," Farrell said. "We still need to see some uptick in the overall stuff and continued building of pitch count."
Rick Porcello, Chris Sale, Eduardo Rodriguez and Steven Wright are scheduled to start the Red Sox's first four games. Because of a day off April 4, Porcello will be able to pitch the fifth game on normal rest on April 8 in Detroit.
If Pomeranz isn't ready to start the next day, the Red Sox likely would call up right-hander Kyle Kendrick from Triple-A Pawtucket.