Mayer agreed to a contract Thursday with the Red Sox that contains a $6.66 million signing bonus, Chad Jennings of The Athletic reports.

EDGE Analysis

Mayer, an 18-year-old shortstop from Chula Vista, Calif., was the No. 4 overall pick in this year's first-year player draft. After signing, Mayer took batting practice and participated in fielding drills prior to Thursday's game against the Yankees. The next stop is Fort Myers, where the 18-year-old will prepare for his professional debut in the rookie-level Florida Complex League.