I think Starlin is probably a sleeper for most people. He’s really raw, but has held his own in Daytona after a 3 level push. Very toolsy kid, Tim Wilken compared him to Tony Fernandez IIRC. Expectations are that he’ll stick at short.

That said, I think the OP was looking for pitching assets. I’m assuming you are looking for starting assets, so some Cubs guys currently in the minors that, IMO, are worth paying an eye on
 (sleepers, granted, with the Cubs system, most everyone is a sleeper outside the top few)

AAA - Esmailin Caridad/Mitch Atkins - Fringe rotation options. Caridad showed better velo in Arizona out of the pen, so he might get shifted there.

AA -

Casey Coleman - I think he’s a possible middle of the rotation arm. Needs some more work, has 3 pitches, working on a cutter/slider supposedly to add to the mix. Legacy kid, hasn’t been fulltime pitching that long. 15th round last year.

Marcos Mateo - May end up in the pen, but has electric fast/slide combination.

High A -

Dan McDaniel - Power righty was dipped in from the pen last year in shortseason, but thrown into the rotation at Daytona. When on, good low 90’s sinker coupled with a curve and mixing in a change/slider/4 seamer.