Moncada gives Sox a glimpse of the future

Yoan Moncada makes his Major League debut, entering the field in the 7th to play third base and he shows off his arm immediatelyOAKLAND -- Yoan Moncada walked onto the sun-soaked Coliseum infield more than three hours before Friday night's game against the A's, flanked by Red Sox infield coach Brian Butterfield, discussing a combination of defensive techniques, positioning and strategy. The tutelage and preparation of Boston's most prized prospect was already underway.

It wasn't long before the Red Sox finally got a firsthand look at all the 21-year-old has to offer, however. MLB Pipeline's No. 1 overall prospect made his Red Sox debut as a defensive replacement in the seventh inning with…