From Mr. Cox's most recent blog
...What's amazing is that the Sens and owner Eugene Melnyk have committed those dollars to Heatley and now to Spezza without really being certain they can be the players who will deliver the Cup.
I hear you, Damien. How could you possibly be 100% certain that these guys are any good? I have a much better strategy for the Senators. First, you let these guys go and see how their careers play out. Then, in about 10-15 years time, you will have the full body of statistical evidence you need in order to know whether they are any good. At that point, you can probably sign them up for a bargain-basement price.
Neither performed particularly well in the one-sided loss to Anaheim in last spring's Stanley Cup final, but that was their first visit to that stage. Only the passage of time will tell if the Sens have bet on the right athletes.
They had a had a medicore stretch of five games against a very impressive Ducks team. I'm going to go out on a limb and say that isn't a good enough reason to not re-sign them.