The 20-year-old Williams wasn't content to carry the label of four-tool prospect, however.
Following an offseason of working with minor league strength and conditioning coordinator Mike Wickland, Williams believes he has added a fifth tool to his résumé: power.
That power was visible in early spring workouts at the Yankees' minor league complex, and so was the heft Williams added to his 6-foot-1 frame, which carried 160 pounds at the end of August.
"The thing that struck me was how strong Mason got from the end of last season until now," minor league director Mark Newman said. "He was part of the offseason program (in Tampa). He was in a nutritional program and a strength program that began after the season and carried into January. He is up 26 pounds, and balls are flying farther then they used to in batting practice."
"He could run, field and hit, but he was a skinny and physically immature kid. It's weight gained in the right way. He is now a strong kid."
The Yankees didn't want to mess with a good thing, however. Williams, a fourth-round pick in 2010 from a Winter Garden, Fla., high school, finished second in the NY-P batting race last year.
He broke Eduardo Nunez's Staten Island franchise record with 94 hits and set a new club standard with 28 steals in 40 attempts. He had the range to cover any center field in the league, and his arm strength too received above-average grades.
Yet according to Newman, the added bulk hasn't cost Williams a tick of speed or reduced his throwing arm.
"Working in the outfield, he looked as fast as he was last year," Newman said. "He's still a plus thrower. He could turn into a five-tool player at a premium position, and they are rare birds."
• Yankees manager Joe Girardi watched 19-year-old catcher Gary Sanchez extensively at big league camp and was pleased with improvements to his defense and work ethic. "He swings the bat with authority and has an outstanding arm," Girardi said. "He has to play—that's the bottom line.''
• An MRI revealed inflammation in catcher Austin Romine's back early in camp, compromising his chance to win the big league backup job from Francisco Cervelli.