Matchups my dear friend. Bosh toasts the Spurs because they have absolutely no one who can keep up with athletically. Z-bo and Gasol are really no comparison, two totally different games.
And shooters go cold, thats what they do. Three point shooting only gets you so far in this league and GS had no where to really go afterwards. We do.
Spurs have like no meaningful rim protection, going to that after Hibbert will be like Christmas for the heat.
You don't plan to take out Bosh when you have lebron/wade + shooters on the floor. And I really don't know where you were last year but the Heat roleplayers were shit all the way to the end of the ECF last year, and turned it on at the biggest stage.
Watch Bosh feast on this slow frontcourt.