Defensive ratings depend heavily on the team you're on. I watched Vuc in the playoffs. He's not a stopper by any means and he got somewhat exposed on both ends in the playoffs. If it's a talent competition Vuc wins in a landslide but fit is key with where the Kings are at currently.
if Kings sign Vucevic, he will become 4th or 5th option on this team when its all said and done. He won't be producing 20ppg averages on this team and that is fine as long as he is willing to sacrifice his stats for the good of the team and be compensated financially for it.
Its similar to Vlade and Christie in the golden years. You can go to them and get them to score 20 in a game without a problem but they were more than happy to sacrifice their games and score 10 each but allowed the likes of Webber, Peja, Bibby and Bobby to put up their numbers.
Its a great thing to have because when the injuries strike (and they will at some point) you have players capable of stepping up in the times of need by just as happy to take the back seat when required to do so.
We know that Vucevic fits this team in the half court pretty well. He can space the floor for Fox and Bagley but he can also get his stuff done in the post and mid range. A skilled big man. Defensively, he will protect the paint. Sure he will not be a Dikembe Matumbo in his prime but he will be an upgrade on what we had with this team in recent times. He will be going for the blocked shots and he will be going for the rebounds. He is also someone who is a pretty underrated passer. Is he worth the max ($35m) on the Kings? Probably not but that is what it would take to get him here.
Point I am trying to make, on this team he will not be asked to carry the team like he did in Orlando. He will become less relied on offensively and would expect him to do certain things defensively that he is capable of doing. His play off struggles are not unexpected considering what he was expected to do from the Magic. He won't have those expectations here. Fox, Hield, Bagley and even possibly one or both of Barnes and Bogdan will be relied on more offensively than Vucevic. Doesn't mean that he is less valued, just that there is only one ball that has to be shared around 5 players on the court at the time.
Still easily the best fit for us in terms of skills and age. If we are expected just to run and gun at all costs, that is not realistic as 50% of the time in the game you need to get into the half court offense which makes Vucevic pretty valuable for both Bagley and Fox.