Well, chemistry does help alot but I dont think thats the reason why there number 2. They do have a good team, a combination of skilled talent and hardworkers.
I look at the Sens who before were all skilled players, but not heart players but now, in a ironic sense, they have a couple skilled players and a ton of heart players (or bangers). I might call it the Maple Leaf Syndrome because the Sens got beat in the playoffs numerous times by the less skilled team, the Leafs.
That's why I never understood the decision to get Martin Lapointe for the Sens. They didnt need him. They have a ton of guys for that position. They needed someone like Hossa, or a skilled player that could play alongside Fisher, or the first line.