Isaac slashed .289/.449/.605 with three home runs and five strikeouts in 12 May games for Single-A Charleston.
The Rays selected Isaac out of high school with the 29th overall pick in last year's draft because of his bat. The 6-foot-3 lefty-hitting first baseman has 70-grade raw power, and the early returns on his hit tool are very encouraging. In May, he had a 10.2 percent strikeout rate and 20.4 percent walk rate, and his 1.25 BB/K is the fifth-best mark in the Carolina League. He missed two weeks in the middle of the month with an undisclosed injury and never landed on the injured list.