was he ranked in any of the previous seasons?. if not that's probably why he got placed silver.
when i first started playing in season 3. my vary first season. i got placed into Silver 3 after my 10 promos.
i believe this is due to the fact it's a fresh rank. i could be wrong but i think it may or may not calculate your normal games mmr?
But anyway. i got silver 3 after my first 10 ranked games ever!!. He could also be in this situation.
i spent the following season getting placed into bronze 3 and being stuck in bronze for quite some time. Tell me that makes sense?.
First season : S3. Second season: B3 then gets stuck in bronze ahaha.
As for the 2nd guy.. Its quite possible that in those areas he really does deserve bronze. But in other area's like teamfighting or split pushing or csing or whatever the area, he does indeed deserve silver. Also you have to think, he didn't start off fighting those silvers. He steadily climbed up in MMR to be fighting those, Maybe he is reaching the peak of his "skill" and is actually now on equal grounds with the silvers and is not finding it tough to play against them.