Johnson is slated to throw to on flat ground next week and could throw a bullpen session within the next couple of weeks, The San Diego Union-Trubunereports. Johnson is scheduled to long-toss this week and will throw to a catcher on flat ground next week. This is a good sign for Johnson, who is trying to make a comeback after undergoing his second Tommy John surgery last April. At this rate, it looks as though Johnson could be up with the major league club in early June.