That said, I do think Steve has the potential to be high tier. Like
Dr. Yatagarasu said, those blocks can screw with linear recovery (ESAM screamed out of anguish when he saw Pikachu fall victim to this), and the main point is that Steve can choose when to place those blocks. The fact they decay quickly doesn't really matter much when the block itself can impede or even stop recoveries in their tracks. Hell, characters like

,

and

don't have many options to break through blocks safely (and depending on how the block interacts with Grenades it can screw over Banjo really hard). That's not getting into the fact that Steve can choose to use ground moves a la Rivals of Aether's Cragg (IIRC) or go for aerials and contest recoveries like crazy.
Steve's biggest drawback is going to be likely early game neutral vs. swordies and disadvantage, but I'll write in depth once this thread has cooled down.