The MLB legend bestowed the new pseudonym on the Seattle outfielder during a sit-down interview for Fox Sports Films' "Welcome To The J-Rod Show" -- a new documentary all about Julio's journey to baseball stardom.

Alex -- who played for the Mariners from 1994-2000 -- gushed about Julio as part of the special ... saying there aren't many athletes built better than the 23-year-old two-time All-Star.

"What I call him is 'The Perfect Player,'" A-Rod said. "He's got size. He's got strength. He can hit. He can throw. He can run. I am a huge fan of J-Rod."

Of course, Alex isn't in the minority on this take ... Julio has only been in The Show since 2022, but he's already considered one of the game's best.

In 384 games, Julio's tallied 70 home runs, 213 RBIs and 80 stolen bases ... all while recording a .276 batting average. The dude's also wowed at a Home Run Derby, belting out 41 dingers in one round last year.

The Fox Sports project promises to show how Julio's been able to have so much success so early ... and it seems Julio is giving his father a lot of credit.

Check out another clip from the doc, Julio said his dad once bought him a pair of super pricey shoes that took years to pay off ... teaching Julio about sacrifice.