We spoke to the '06 World Series MVP after he paid a visit to Halos spring training ... and he told us Ohtani -- the team's huge offseason signing who can pitch, play outfield and DH -- is the real deal.

But the more interesting takeaway -- Eckstein told us Ohtani's just the beginning of a new wave of super-athletes who can play both ways!!

"If you start looking at more of the lower levels, and especially now going into college, you see that's where the game's going. And he might be the first," Eckstein said.

Eck knows all about trailblazing -- the 5'6'' shortstop paved the way for Jose Altuve and all the other small ballers of today!