I think Hayes is more than a 4th or 5th big. More like a 3rd big who you can rely on to get the job done. From what I've been hearing from Rocket fans they are all disappointed that he is leaving and in many cases would rather have kept him instead of pursuing Dalembert.
Because they ain't bright. He's the scrappy overacheiver fans love, but their defense absolutely collapsed after he took over in there for Yao. Does the best he can, and is a good man defender, but obiously he couldn't stop me as a help defender. Well he could stop me maybe. But not anybody NBA sized.
The sincere sincere hope has to be...well, it has to be something that's really not a great hope. But it has to be that we are still after Dalembert as well, and that therefore Hayes' arrival means that we are moving somebody else. The logical somebody else would be Jason Thompson, who is both a good guy and one of our young semi-leaders, so Hayes arrival to set a defensive tone and give leadership is less impactful than it would have been.
Two ways you could make me happy about this move would be:
1) sign Hayes, sign Daly, and then because he always had the utmost respect for him, nab Battier as well, possibly in a sign and trade for Thompson (althoguh the sign and trade would help a potential rival one day field a monster frontcourt of its own). That would add/retain three elite defensive players in one offseason and might well be enough to spin our defensive culture around. Then again, we've seen what Battier and Hayes could do alone on defense in Houston, which is to say not much. Individually they were strong, but Houston got bad defensively once they lost the big guy insdie. Maybe bringin back Daly and have some big youn stud atheltes as well would be enough for a different outcome. Could not hurt at least.
2) sign Hayes, not sign Daly (in which case in alarming fashion you really have replacemed Dalembert with Hickson), and thus retain Thompson, but then take the huge chunk of free agency money you still have and spend it to bring Kirilenko back over from Russia. Then you add two top defenders, and try as Utah did to get your shotblocking from your SF. Of course here again it should be noted that Utah's lousy frontcourt defenders/Kirilenko as lane protector theory left that team defensively weak in the middle as well. I should note that any approach like this likely leads to continuing foul problems for Cousins as well because then he has to try to play shotblocker/lane clogger, something he is not naturally fit to do, as once again your Sacramento stubbies would trot out a frotncourt without a single guy more intimidating as a shotblocker than Brad Miller.