Not true whatsoever. He's improved in pretty much every facet. If he had the minutes to qualify, his rebounding rate would be in the top 10 in the NBA. He's drastically reduced his TO%, which was a huge issue for him his rookie year. The efficiency is better raising his FG% by 3% and his FT% by 9%.
All in all, he's a solid back-up big. Not what you from a 5th pick obviously, and certainly not over Drummond or Lillard, but he's still also only 22 years old and he's far from a guy who's going to bust out of the league, like many thought last season. Plenty of time to develop and tap into his potential. The rebounding prowess seems to have translated, which bodes well for his future.