The only reason Sheldon isn’t as irritating on BBT as he is on YS is there’s always Walowitz (sp?) to compare him to. He’s the last reason to watch YS, the rest of the cast is the draw. There’s also the incongruity that the child Sheldon comes off as more adjusted and mature than adult Sheldon. The kid version is supposed to be seen as evolving (devolving?) into the adult version but they never quite got there. Maybe a full final season would have closed that loop better. All that being said, the poignancy of the last couple of episodes with his attempts to come to grips with George’s death got the room dusty.