Edwin Jackson doesn’t have to worry about being dropped from the Cubs’ rotation. “No, we’re going to stick with him,” manager Dale Sveum said. “It’s a long season. There’s still another 20-plus starts here to fix this and get it going.” Jackson is 1-7 with a 6.11 ERA. He signed a four-year $52 million deal to be a starter, so the Cubs aren’t going to give up on him yet. “You have a commitment there and you have to stick with the commitment,” Sveum said. “Coach him and teach, but it’s not like he’s a kid. Sometimes you have to do it yourself.” After Thursday’s loss to the Pirates, Sveum said he needed to see Jackson pitch with more “conviction.” Asked Friday what he meant by that, Sveum said: “When you come out, we need to be full velocity … instead of gradually getting into that to where the game gets away from you.” Draft watch: The Cubs have narrowed their choice for the second overall pick in the June draft to four college players: right-handers Jonathan Gray (Oklahoma) and Mark Appel (Stanford); and third basemen Kris Bryant (San Diego) and Colin Moran (North Carolina). Top brass Theo Epstein, Jed Hoyer and Jason McLeod were in Northern California on Friday for a “draft doubleheader.” Bryant played in the WCC tournament in Stockton, while Appel made his final regular-season start in a home game against UCLA.