Maybe that explains some of the inconsistency.

The Yankees announced Tuesday afternoon that ace righthander Masahiro Tanaka underwent arthroscopic surgery earlier in the day at the Hospital for Special Surgery in Manhattan to remove a bone spur from his right elbow.

According to the club, the spur "was pre-existing, dating back to his pitching career in Japan."

The Yankees said recovery time is about six weeks, with Tanaka expected to begin a throwing program afterward and to be ready for the start of spring training in February.

The 26-year-old Tanaka, in whom the Yankees made a $175-million investment in January 2014, went 12-7 with a 3.51 ERA in 2015. In his 2014 rookie season Tanaka was 11-1 with a 1.99 ERA before suffering a slight tear in his right ulnar collateral ligament. The righthander finished that season 13-5 with a 2.77 ERA, setting up a year-long narrative about the inevitability of Tommy John surgery on the elbow, which has yet to occur, though his velocity was down a tick in 2015.

Though the Yankees played down the dip in velocity, more than a few opposing team scouts and talent evaluators felt Tanaka pitched tentatively at times and did not seem as confident pitching inside.

This is the third physical issue Tanaka has had. Along with the UCL tear and bone spur, Tanaka missed time this season with a right forearm strain and right wrist tendinitis.

After allowing 15 homers in 2014, that number ballooned to 25 this season.