Wood's career eFG% is 57.3 and his career TS% is 60.2%. For a guy with a career 3PT rate of 30% that is a pretty darn efficient scorer. Now his efficiency is down this year, but Houston is so bad I think it is more of an outlier than the norm. He is not a + defender, but he is an excellent rebounder.
Wood turned 26 at the end of September, so he almost exactly 2 years older than R. Williams. Wood is a significantly better player though, stays healthier, and hasn't done anything to stop Houston from tanking. That doesn't mean Houston wouldn't trade him, but it will take a lot more than Williams for that to happen and they don't exactly need a bunch of a future picks as they own a bunch of them.
Wood, Gordon for Richardson, Langford, R. Williams, Hernangomez
That makes more sense for Houston as they shave a bunch of salary this year and long term, get a look at Langford and get the longer similar contract in Williams to Wood. That still might not be enough, but it at least seems like a more reasonable trade.
Wood is not an efficient scorer and his advanced defensive numbers suck.
Career totals for TL and Wood for PER, TS%, Total Rebound%, and defensive box +/-. Don't see how you can claim that he's significantly better than Williams.
Rk Player PER TS% TRB% DB+/-
1 Robert Williams 23.4 0.721 18.3 2.9
2 Christian Wood 20.3 0.602 16.4 -0.6
because minutes and games played actually matter. what sort of offensive option you are matters. where you take your shots matters.
They are playing similar minutes this year, though Wood has played in 5 more games. Wood is averaging 16.4/11.3/2.4 while Williams is at 9.4/9.6/1.4. Over 71% of Williams' shot attempts are from 0-3 feet. He has over 25% of his attempts from 3-10 feet. He has taken 2.5% of his shots from longer than 10 feet. He has no range. He is easy to defend because of it and he won't take shots unless he is basically wide open. Wood on the other hand has almost has many 3 point attempts (33.7) as he does attempts from 0-3 feet (36.4). He takes shots from all over the court, making him far more difficult to actually defend. Wood is a better rebounder and passer. Williams is most certainly a better defender, but he also turns it over a much greater rate. And Wood's shooting numbers are all down this year playing with a lot less talent and taking more of the defensive focus.
So I say Wood is significantly better than Williams, because he is, both in the fact that he plays more, but also when he is on the court he is just better.