Howard was scheduled to throw two innings Monday against the Yankees but was scratched due to back spasms, Matt Breen of The Philadelphia Inquirer reports.
Howard had been looking good this spring, with his velocity and conditioning both in a better place than they were during his disappointing rookie season, but he already appeared likely to open the year in the bullpen or minors due to the offseason acquisitions of Matt Moore and Chase Anderson. While the back issue doesn't appear to be a particularly serious one, it could keep him off the Opening Day roster given that his spot already appeared precarious to begin with. Even if he fails to crack the rotation to start the year, however, he should be one of the top options to step into a starting role when someone ahead of him gets hurt, so he could certainly still earn a fair number of starts at some point this year.