If you think Favors is so replaceable, tell me when the last time the Jazz had a player who was so good defensively? The last time I can remember was Mark Eaton, and he retired in like 94. A defensive player the caliber of Noah and Chandler is not simply replaced. Seriously. Just look at the teams they are on. The Bulls are a perennial contender (when rose is healthy) the Knicks finally look like a good team, and the Mavs only won a title when they got Chandler. The only other guy as good as them defensively is Dwight Howard, and he is not that great offensively either. If Favors turns out to be 80% of what Dwight Howard used to be, then we will be well on our way to a championship.
The last time we had that good of a defensive player? Well...we did have this guy called Andre Kirilenko play for us a couple years back. Remember him? He was pretty decent at defense.
Oh and Favors isn't as good defensively as those guys...yet. He has the potential to be that good, but we'll see what happens.