I'm not surprised that these rookies are bonding well and quickly...

They are pretty much cut from the same cloth, psychologically.

Football smarts
Work ethics
"We, not me" personalities.
Football first, last, and always guys
High character to a man
Football players rather than merely great athletes

Know what? The kind of players that are really easy to root for. I'm loving this crop of rookies, including the UDFA's.