He added bulk because he played PF in Greece. When he was in Denver he played SG-SF and probably weighed 15+ pounds less. He used to even defend Kobe at times.
He def needs to lose weight to be more effective in the NBA because he will play at SF, not PF. He was fairly athletic for his size in Denver and I'm hoping that rehabilitation for the microfracture surgery will get him into SF shape. At the same time I hope that the injury will not limit his athleticism. Amare seems to have recovered well.
In terms of the bigger picture, people can't really evaluate Kleiza since he played injured all season. His numbers were dismal but he must of been in some serious pain to make it to February. Can't really judge a player who wasn't playing at full health.