That is true about him being 6'11", but him being so skinny should help him a little as well. Shelden weighs a lot more, but he had a better no step vertical and jumped only 3/4 of an inch lower than did Aldridge in the max vertical. Shelden Williams also had a better lane agility score despite being 25 lbs. heavier. Throw in the fact that Shelden more than tripled the number of bench press reps that Aldridge had and it pretty much seals the deal that Shelden Williams had better test results. That said, I'd rather have Aldridge because he's a little taller and has a much better jumper with better range, but by no means would I give up Mike Bibby to get him.
Also, I am assuming that when you say "Aldridge destroyed Williams when they played each other," you are referring to Duke's absolute beatdown of Texas when they won by 30 points. Let's take a look at their stat lines.
Williams- 35 min., 7-12 shooting, 23 points, 6 rebounds, 4 assists, and 5 blocks
Aldridge- 40 min., 8-13 shooting, 21 points, 6 rebounds, 0 assists, and 0 blocks
So let's see, Williams had more points, the same amount of rebounds, 4 more assists, and 5 more blocks in less minutes than Aldridge. And Williams' team won by 30 points. Are you sure Aldridge destroyed him?