Yeah we were telling the same thing before Amsa came out. :x
A lot of people were saying they were unsure of Yoshi, some saying he had a lot of potential to be high tier (Sweden). Yoshi was often admitted as a wild-card. With that said, it's pretty clear, especially if you look at the Japanese meta, that Yoshi is, at best, Pikachu level (and I say this while finding Pikachu over-rated), meaning he'll never actually be a "tournament viable" character like Fox or even Sheik/Peach.
Characters like Young Link, Doc, Ganon and Ness still have a lot of room for optimization, but they'll never be Yoshi stories. They lack Yoshi's (long-known) absurd movement and invincibility abuses -- there's nothing groundbreaking with them.
The biggest wild card at this point in the meta is, imo, Ice Climbers.