From ESPN TrueHoop Affiliate NBA Playbook:
While Valanciunas is staying overseas for one more season, the Raptors’ front office and new coaching staff have big expectations for him on the defensive end. While doing my player comparisons for Basketball Prospectus, Kevin Pelton’s player similarity scores showed us that Valanciunas compared most closely to Tyson Chandler. Funny enough, the man who just coached Chandler and will be coaching Valanciunas in the future saw the same things...
Despite the reputation Bargnani has for being soft and a terrible defensive player, I think the combination of Valanciunas and Bargnani can work on the defensive end. While Raptor fans are probably rolling their eyes at me, because both Valanciunas and Bargnani have strengths and weaknesses right now defensively. Luckily for them, their strengths compliment each other well, and they should be able to hide each other’s weaknesses.
Luckily for Bargnani and the Raptors, Jonas Valanciunas’ biggest strength right now is his help defense/being that last line of defense, blocking and bothering shots, but never really getting too far away from his man and being in position to defend him as well: