It's a common misconception because people equate rebounding and hustle with defense as a result of certain players who made a living that way in the past, mainly Dennis Rodman and Ben Wallace. Evans is a poor man's version of those 2 and an inferior defender. He is pretty aggressive and scary looking though.
Rodman was not JUST a rebounder. He was arguably the greatest rebounder ever, but he was also a great all around defender. A big part of what made him a great rebounder, was the way he would fight for position in the post. He used that same attribute, to keep elite offensive players out of their comfort zones and frustrate them. Plus he could guard 3 positions, which gave his teams added flexibility on their other defensive matchups.
Ben wallace wasn't on Rodmans level in terms of overall defense, but he certainly wasnt just a rebounder either. He was one of the best at weak side help in the post, and fast enough to get steals (more like interceptions) on any careless pass across the lane.
You want to talk about a guy with poor defense thats camouflaged by his rebounding, I'd say Kevin Love. Rodman and Wallace actually did play some D.