I thought along these lines as well before, but after looking back at more of Lucic's history, I think he actually has been historically a rush scorer. He's actually pretty bad at puck battles along the boards. When he was in Jr, he was like a wrecking ball coming down the ice with the puck or on a rush. He could just plow through situations and hammer pucks home. He was a physical freak of nature, this huge body with decent speed and athleticism. He's slowing down now though, and D are getting better and better every year at separating pucks from players without needing to physically engage. Stick checking is becoming a science that more and more NHLers are learning to master. The league just keeps getting faster as well, and every year more large players have good speed.
Lucic's lack of stick skills, combined with how he's been slowing down while the rest of the league speeds up are both hurting him in a big way. Kudos to him working on speed this last summer though. I hope he at least gets back to the 40-50 point range. This year very likely will be the best of the rest of his career.