What makes a player an X-factor? There's no hard-and-fast definition; it's a "know it when we see it" situation.

For our purposes, we'll define it as an enigmatic or injury-prone individual with the potential to take a leap forward; a fading veteran who could provide a late-career surge and/or value as a trade chip; or a talent-laden prospect with a path to playing time. Superstars and steady role players need not apply.

In all cases, high-ceiling outputs by these 30 guys—one per team—would give a significant boost to their respective clubs.

American League East

Baltimore Orioles: C Chance Sisco

When top Baltimore Orioles catching prospect Chance Sisco made the Opening Day roster, it was unclear how he'd share duties with established backstop Caleb Joseph.