The thing to note is that this little sick Leonin is producing roughly the equivalent of a threat as a Delver and a Geist
The buff Don Andres gives to stolen creatures as well as the Treasure tokens he generates when you cast noncreature spells that don't belong to you are nice, but they're far from enough to make stealing cards worthwhile (especially because the treasures enter tapped)
They also have the opportunity to attack first, which can give them a unique tactical advantage, they said
A card that misses in Standard might still be perfect for your cube its okay to trust your gut, follow a less-trodden road, and/or update more slowly to let the playtests percolate
...And More Goblins The most important part of a Krenko, Mob Boss deck is getting enough Goblins into play for Krenko to do his job
If you target a face-down Morph with Maelstrom Pulse, only that one Morph will be destroyed