A quarter of the baseball season has passed us by, and, due to combinations of injuries at the big league level and hot starts on the farm, it's becoming clearer which prospects have even better chances to make their major league debuts this year. Below is one potential call-up from each club whom you should anticipate and be excited about and who might have an impact on a playoff race while providing you a glimpse of a hopeful future.
Arizona Diamondbacks: RHP Yoan Lopez. Lopez's tenure had been little more than infamous until 2017, when his fastball velocity ticked up 5 mph. Once a prospect albatross teams had a hard time scouting due to inconsistent playing time, Lopez is now throwing 95-99 mph complemented with a plus slider. He's got bat-missing stuff, and the big club is working through a rash of pitcher injuries, so he'll likely be up at some point.
Atlanta Braves: RHP Touki Toussaint. Touki has stretches in which he's throwing strikes and dominating, and others when he isn't. His lack of control might make it difficult for him to throw five or six efficient innings as a starter, but his stuff is so good that he's poised to have late- or multi-inning value in the bullpen even if his command never develops. If Atlanta remains competitive throughout the summer but its pitching health issues continue, Touki could get the call.
Baltimore Orioles: RHP Hunter Harvey. Harvey's many injuries have kept him off the mound for most of the past four seasons. He has made just seven starts and has already thrown more innings this season than in any since 2014. Though it might behoove Baltimore to preserve his health by limiting him to the bullpen eventually, Harvey is still just 23 and has retained his mid-90s fastball and plus, hammer curveball despite the injuries.