In the beginning of camp, Eduardo Nunez was reticent about the changes Mick Kelleher was attempting to make with his throwing motion.

Kelleher, a former big league infielder and current Yankees first base coach, decided before camp opened a change to the error-prone Nunez’s throwing motion had to be made.

“In my opinion and Joe [Girardi’s] opinion, something had to change,’’ Kelleher said. “To play shortstop you have to be an accurate thrower. It wasn’t about catching the ball, it wasn’t that.’’

Some voices believed Nunez belonged in the outfield. Others suggested Nunez become a full-time designated hitter at 25. General manager Brian Cashman didn’t think Nunez’s bat was strong enough to play a corner outfield spot. So the Yankees’ party line was Nunez was a shortstop despite committing 18 of his big league errors as a shortstop.

So, Kelleher was entrusted with making Nunez’s above-average arm — in terms of strength — more accurate.

“Before my arm action was long, never short,’’ said Nunez, who made seven errors at three positions last season, four of those on throws. “All my life it was long. Now it’s short and it feels good so far.’’

Nunez admitted the change wasn’t easy.

“It was uncomfortable,’’ said Nunez, who used to catch the ball and swing his arm around the back of his body before releasing it. “Now, it’s much better. I have worked on it since the first day of camp. The first few days of camp it was really bad. Now it feels better. I have made the adjustment.’’

Kelleher got Nunez to catch the ball and bring his arm to shoulder level before releasing. His belief was Nunez wouldn’t suffer a decrease in arm strength while trying to be more accurate.

“We worked on it every day since he got here,’’ Kelleher said. “We wanted him to throw like [Derek] Jeter throws, like Robbie [Cano] throws. We wanted him to shorten it up.’’