TAMPA, Fla. -- Frankie Montas is continuing to experience discomfort in his right shoulder and has decided to undergo arthroscopic surgery, Yankees manager Aaron Boone said on Wednesday. It is possible that the right-hander could return in the second half of the season.

Montas¡¯ surgery is scheduled for Tuesday. He had already been expected to miss the beginning of the regular season due to lingering discomfort and inflammation, which delayed Montas¡¯ offseason throwing program.

¡°It¡¯s been a couple of different shutdowns where he was getting built up,¡± Boone said. ¡°He was building back up and just still wasn¡¯t quite right, so now we¡¯ve gotten to the point where he¡¯ll scope it and we¡¯ll have a better idea of the time frame once that happens.¡±

Montas, who turns 30 in March, is eligible for free agency after this season. He was 5-12 with a 4.05 ERA in 27 starts for the A's and Yankees last year.

¡°Best case is, he would be back late in the season, but we¡¯re really going to know a lot after the 21st when they know specifically what they have to do in there,¡± Boone said.

Montas experienced inflammation in his pitching shoulder with Oakland, forcing him from a July 3 start. He returned to the mound on July 21 and made two starts before being acquired by the Yankees, who sent pitchers Luis Medina, JP Sears and Ken Waldichuk, plus infielder Cooper Bowman, to the A¡¯s for Montas and reliever Lou Trivino.

¡°We knew when we traded for him that he had missed time with the shoulder,¡± Boone said. ¡°That¡¯s the nature of a pitcher, though. They¡¯re able to get back on the mound.¡±

The Yankees envisioned Montas as a difference-maker, especially for a potential playoff showdown with the Astros, given his strong career performance against Houston. But Montas was just 1-3 with a 6.35 ERA in eight starts before aggravating the injury on Sept. 16.

¡°With all these pitchers, you¡¯re going to have similar things,¡± Boone said. ¡°That¡¯s why, especially with shoulders, they don¡¯t race into shoulder surgeries all the time. You can treat these things and sometimes these things lay dormant. Sometimes they¡¯re asymptomatic, sometimes they become very symptomatic. For Frankie, it was just a nagging thing that didn¡¯t allow him to get over the hump.¡±

New York¡¯s rotation projects to feature Gerrit Cole, Carlos Rod¨®n, Luis Severino and Nestor Cortes, with Domingo Germ¨¢n and Clarke Schmidt among those battling for the No. 5 spot.

¡°We feel very confident in those that are now going to get an opportunity,¡± Boone said.

Pitching coach Matt Blake said that he is optimistic Cortes will be ready for Opening Day, despite a right hamstring strain that forced him out of the World Baseball Classic.

¡°He seems to be in a decent spot,¡± Blake said of Cortes. ¡°You never want him to come in with a hamstring issue. I think, as a precaution, we¡¯re just kind of slow playing that a little bit. I feel pretty good about watching his catch play and where he¡¯s at. Overall, maybe it¡¯s better than what it could have been.¡±