You don't have to be a shot-blocker to be a good help defender. You have to be someone who rotates & switches when he is supposed to, and knows when to double-team and still get back to his own man quickly. I haven't seen anything that would make me think that Hayes doesn't do those things. Of course, it helps when you have someone who comes from the weak side and blocks a shot, but I would point out that Donte did that more than anyone for the Kings last season. Most of Dalembert's blocks always seemed to be against the man he was guarding. I would also point out that the biggest part of playing good team defense is TALKING, and that is something the Kings did very little of last season (including Dalembert).
Not the way it works in real life.
You can be a good help defender wihtout being a shotblocker, you can NEVER vbe a defensive anchor without being one. The only elite defnsive teams who have got it down without a major shotblocker have been teams with seriously all world perimeter defenders. Not just 1 either. But 2, 3 of them at a time amongst the best of the league at their positons. The why of it is very simple. The shotblocker protects EVERYBODY. He's by far the most important defensive player on the floor because he plays behind everybody and is back there still inbetween the pposing player in the hoop for every single one of his teamates. The greatest SG defender int he world is till out there at SG. He's not going to have any effect on the SF in the corner, the PF posting up on the other side of the lane, etc. The shotblocker has an effect on all of them. Changes their offense. Deters them with his mere presence. So you choices are a) get a single player, the shotblocker, to stand back there and make every single one of your other defenders better by deterring forays to the rim by opposing players. Or get 2,3,4 all elague type defenders out on the perieter so that they never need the help. It can be done the second way. But its FAR easier and more logical to do it the first way. Get your defensive anchor and have a lot more room for error on the perimeter.