Lot of things to be settled.  But if the Jays end up spending 100mill (50mill posting + 50mill contract) for 5 years of Darvish I would consider that way too much of a risk.
Strike zone is so much bigger there.  Why these guys coming over have terrific K/BB ratio's.  Strike zone gets tighter and it changes everything dramatically.  An extra inch at here and there is major.  Trust me.     
 
Give me Buehrle at 6/90 then Darvish for 5/100+.  You are rolling the dice that Darvish is an ace.  Give me the proven guy for 15mill/year.