Though you could argue Detroit was a less successful team after splitting them up. If I'm not mistaken they split after their cup win. Adding Hossa saved them for a season (and got them back to the finals), but thereafter the Wings offence never looked quiet as dangerous, nor did Zetterburg or Dats. Of course other factors where at play there, namely losing Rafalski and Lidstrom starting to slow down and actually look human.
Yes, it was probably part of the reason they split. Everyone I think saw that the team started to lose a step after their cup and (I would argue) their loss in the final the year after. It was logical to split them, and the team had success after as well. But not as before.
Anyway, neither were McDavid/Crosby quality so that obviously changes the dynamic a bit. McDavid will be ok with or without Drai, Drai might struggle without McD. Which also is fine by the way, he is 21.
Of course this contract is a bet and a risk. To me it seems in line with how the cap-world works. You sign for potential all the time, and betting on Drai is a very good bet so I don't mind the contract at all. It can back-fire though.