It's silly to say we need one or the other. We need both defense and offense. A team full of freshmen and a bare bones roster is almost never going to play real good d, and we didn't. We need both...
As far as these kids go, from what I can gather, Clark is quite a good offensive player. He's more of a wing than a PF as per Michigan state fans, and put up high percentages in his ft and 3pt stats considering his minutes played. They seemed to say his defense was fair and that he didn't get enough rebounds, but per minutes played, 2.5 rpg isn't bad for only 10 minutes a game. He's a very good athlete, real strong, long arms. Looks like he can certainly help us as there are pages of Michigan state fans who didn't want to see him leave.
As far as Simon, he seems a very gifted athlete who can play both guard and forward spots. Looks like he excels going to the rim and will likely be a good defender off the bat. Zona fans don't know if his shot is quite developed yet, but again the kid barely played. He shot .500 from the field and was 1 of 3 on treys for the season which doesn't seem big enough sample size. Their impressions seemed to be that he has a high ceiling but they were bringing in such high level talent that he minutes were pinched.
Both guys seem to be ones who had limited minutes with solid stats. Just look at the level of players both Zona and Michigan state are bringing in at those positions... Some of the best recruits in the country. As they say, " one man's trash is another man's treasure". I get the feeling like that is the scenario here.