The difference here is that they're no longer starting Channing Frye at C, but rather an
actual Center in Lopez. Frye was pretty good at stretching the floor for a few weeks, but he became pretty useless after everyone figured out that you can't leave him open outside. The addition of Lopez has instantly improved our defense and rebounding. In the the last 10 games, the Suns are the
2nd best rebounding team in the league. They're also tied for 3rd in blocked shots and 9th in opponents' FG%, while still maintaining a high-powered offense.
I completely understand your skepticism, but I think our "toughness" is for real this time.