In just his first professional season, Will Warren has made it to the pivotal Double-A level. A key factor in the former Jackson Prep star’s rise is a pitch he discovered and refined in minor league spring training with the New York Yankees. It has been labeled the “unicorn slider,” a bolting breaking ball that compliments Warren’s low-90s fastball. “I’ve never seen a pitch like it,” catcher Josh Breaux, Warren’s teammate with the Somerset Patriots, told nj.com. Warren, 23, a 6-foot-2 right-hander, takes a 2-2 record and 3.92 ERA into his fifth Double-A start tonight against Hartford at Somerset’s TD Bank Ballpark. Warren told nj.com that his quick rise in the Yankees’ system is “unreal.” Warren went 7-0, 1.39 ERA, at Jackson Prep as a senior and signed with Southeastern Louisiana, a good but off-the-radar NCAA Division I program. He spent four years with the Lions, posting a 3.90 ERA in 53 games. The Yankees liked something they saw and drafted him in the eighth round last summer. He made his pro debut this season with High-Class A Hudson Valley, going 2-3, 3.60, in eight starts before earning the promotion to Somerset of the Eastern League late last month. All told, he has 56 strikeouts and 17 walks in 55 2/3 innings. Warren still has work to do, of course, but he is rated the Yankees’ No. 27 prospect by MLB Pipeline, which notes that his slider could become a “high-leverage weapon” in the big leagues.