The long-awaited influx of top prospects is finally underway for the A’s, who have been forced to wait to debut their two best young arms due to injury setbacks.Ahead of Tuesday’s game against the Yankees, Oakland will reportedly promote left-hander A.J. Puk from Triple-A in hopes he’ll shore up an inconsistent bullpen. Puk, the No. 6 overall pick in the 2016 MLB Draft, is eventually expected to become a starter for the organization. For now, though, his high-90s fastball and sharp slider could make him a primary late-inning option for manager Bob Melvin at a crucial point in the season. MORE: A’s ‘very happy’ post-deadline despite apparent bullpen holesShould the A’s make the wild card, Puk would additionally have the chance to join a historic list of first-year pitchers to break through in October. There are several of those potential hurlers in MLB this season, most notably Dodgers rookie Dustin May, who is also slated to log significant postseason innings.Oakland was 1 ½ games back of the Rays for the second wild card entering Monday. When the A’s were unable to complete a deadline deal for another relief pitcher at the July 31 deadline — despite attempting to do so — they held hope Puk and fellow left-handed prospect Jesus Luzardo could emerge. Luzardo is on a rehab assignment from a strained lat and is in position to join the MLB roster soon.Oakland’s bullpen has been shaky at times over the past month, though its most problematic arms banded together for seven scoreless frames in an extra-inning victory this past Friday against the division rival Astros. Last year’s closer, Blake Treinen, has a 4.67 ERA. Top 2018 setup man Lou Trivino has a 4.75 ERA. There is room for Puk to grab high-leverage opportunities within a couple of weeks.