New York Yankees manager Joe Girardi said Tuesday he is optimistic about Masahiro Tanaka's ability to take a leading role in the starting rotation in 2015 following a serious elbow injury this year that sidelined the right-hander for over two months.

Speaking to reporters at the Baseball Winter Meetings, Girardi said he is optimistic regarding Tanaka's comeback and that of ace lefty CC Sabathia, but added that question marks remain and called the depth of his starting rotation his biggest concern.

"There are some concerns, because of guys coming off injuries. Ivan Nova will not be ready for Opening Day, but he's had a great rehab," Girardi said. "Tanaka's rehab went well and he pitched well at the end of the year. CC's rehab went well. But as we've seen, you need more than five starters. We're going to have to see where our rotation is."

Tanaka, who led the team in wins with a 13-5 record despite missing two months due to elbow injury, pitched two games at the end of the season.

"We're counting on him (Tanaka) to make his 32 starts," Girardi said. "But that's something we're going to have to look at as the season progresses."