The goal is to build up his arm strength without the added concern of locating pitches or facing live batters.
"I just want to get back to throwing hard on flat ground," Janssen said. "We think the transition to the mound is going to be really, really quick. We're trying to extend the reps and the velocity, and then that transition will be fast."
Janssen began the spring by throwing off a mound. He wasn't going at 100 percent, but there were still some concerns expressed by pitching coach Pete Walker. The belief was Janssen was focusing too much on his mechanics as opposed to just getting his arm loose and back to full strength.
That prompted last week's change. It could be viewed as a setback, but Janssen is at least publicly optimistic that he will be ready for Opening Day. Despite that, he did admit that it was comforting to know that the Blue Jays have a capable replacement in Sergio Santos who could start the year in the closer's role and buy Janssen a little more time to get ready.
"It's weird, we're talking about time and dates, but we haven't even hit March yet," said Janssen, who recorded 22 saves in 25 opportunities last year. "Sure, there's going to come a point when you're pressed for time to make Opening Day realistic, but I don't think we've hit that date yet.
"Not that we even want to consider it, but if it's a week or two late, it's not the end of the world, either. It's only fair to the team and fair to myself. You don't want to underachieve because of something else or because you took a shortcut."