I'm certainly not saying Onstad is a great keeper, but I don't rate Langfield or Soutar at all and the SPL isn't full of quality keepers, and you weren't pointing out better players if you look into who you commented upon (maybe the exception is Robinson who has a number of Welsh caps and could probably play in the dons starting eleven). You pointed out average players in MLS as did I, guys who play most games. Would you take a 32 yr old Dichio or a 40 yr old Brewster in your squad? They are comparible if you ask me. Paul Dalglish won the MLS = Bob Malcolm winning the premier league. There are plenty of mediocre Scottish players would get overly recognized too - look at the Rangers and Celtic diddies who have been selected for Scotland before quality and more deserving players (i.e. the clowns that play instead of Russell Anderson.)
I'm not arguing MLS is better but I think they are comparible leagues. I've seen terrible dons games in the past and great MLS games and vice versa. Freddy Adu is a decent player with plenty of talent but remember he's only 18. He's been overly hyped up by MLS to get attention to the league but that is American sports - the world series, world champion San Antonio Spurs etc. It's not the world but that's America.
Johnson isn't the best player in MLS and I'd say Angel, Donovan, Albright, Johnson, Mapp, Ching, Mastroeni for example could all start for an SPL team plus there are loads of good up and coming players. I heard Danny Szetela is being linked with Rangers being one. It's a very new league and will only get stronger as players develop and gain experience. MLS will just get stronger (as will American 'soccer' in general) - It pains me to say but I'm not as confident about Scottish football.