What is the thing most likely to keep a big league executive awake at night?

The answer might vary, but high up on the list for all of baseball's decision-makers would surely be innings. Just plain, simple innings. As in, who is going to pitch them and for how long? That issue, by itself and before we even get into how well the innings are pitched, is the gnawing problem for all those who are charting a course for the coming season.

Never has that riddle been harder to grok than it is right now, less than a month before the 2021 regular season begins. The innings problem was already a priority to-do item for execs around the game before last season and has been for eons. It's also a 21st-century kind of dilemma and, ironically, one for which baseball's honchos have only themselves to blame. With teams leveraging advanced data more and more each year, and deploying small legions of analysts digging for every marginal edge, all run-prevention innovations seem to lead back to a common need: more pitchers.

That means building bullpens is more important -- and complicated -- than ever before. How many relievers will teams need and where will all those extra arms come from?