IMO we let Teddy walk because his game was hardly different than "old man" Brees' game...high percentage short throws 99.5% of the time with an intermediate ball sprinkled in for good measure. I think CSP wanted a different brand of football, that's why he let TB walk without putting up too much of a fight.
Now, that different brand, was it TH bullyball or JW big arm ball...is the question and I think CSP really was up for both.
Also, it didn't help that Brees was coming back for another season and his market heated up a little. But lets not act like he stunk up the joint while he was here.