1- Might wanna check that point again. Bjergsen was one of the most hyped players when he burst onto the EU LCS scene and was pretty popular at the time, no to mention really good (Otherwise TSm wouldn't have taken him). Same with Sven actually, he got to worlds with SK and they actually beat TSM during the group stage (the second game, he was banned for the first one and missed the first 3 games of groups). If i'm not mistaken, he was was in one of the top 3 teams in EU.
2-Again, look at my bjergsen point above, granted he's better now than he was back then (and who wouldn't improve after a couple of seasons?). Just look at froggen, he was the only reason EF even stayed in the LCS these past couple of splits.
3-Point being?
4- In 7 seasons, they've "rekt" EU 3 times: IEM 2015 when TSM won it, MSI of last year with CLG's run (and even then G2 had the whole vacation meme going) and this rift rivals. Just compare the overall success from both regions internationally since season 2 (not even counting season 1 where EU won worlds cause barely anyone played back then): NA has never made it to the semis of worlds whereas EU has made it every season bar season 4. NA only has 3 IEMs win, EU has a 7 wins. For right now, sure NA>EU but let's wait for worlds before saying NA has rekt EU many times before. EDIT: make that 8 IEMS for EU, forgot one by FNC.
5- Like I already said, he obviously became better after he left, but then again, he was a rookie with extreme mechanical skill in EU, he's obiviously gonna get better with more experience..