We asked ESPN's Insiders to give us their take on what the single most important question each team has to sort out heading into the 2017 season. Getting a happy answer will be much more difficult for some of the 30 ballclubs than others.
National League
Arizona Diamondbacks: You should worry about this team's bullpen. They have a lot of question marks after you get past Randall Delgado and Jake Barrett. They're hoping veteran closer Fernando Rodney has 30 to 40 bow-and-arrow celebrations left in his arsenal, and they also have to hope for improvements from Silvino Bracho, Zack Godley and Andrew Chafin if they want to be competitive. -- Jim Bowden
Atlanta Braves: Will Bartolo Colon and R.A. Dickey be on the roster on Aug. 1? Some view the Braves' farm system as MLB's deepest, but they didn't have any young starters ready for the majors and some already there have struggled. The Braves signed the two 40-somethings to chew up some innings and maybe help them contend, but if they're out of it, they'll look to deal Colon and Dickey at the deadline. -- David Schoenfield