The main point about this guy is that he works his tail off, cares about basketball, and his skill set still applies in the NBA.
The league is moving towards pace and space, with everyone able to do everything (Durant just played center in the finals for a few minutes at a time, for instance). But you still have use for big bruiser types, especially ones with a little bit of skill. See for instance Stephen Adams, or Andrew Bogut from that original Warriors championship team two years ago.
I mean, we just signed Aron Baynes as the probable starter in the front-court next to Horford. He almost definitely won't close out games, just provide 15-20 minutes of solid defense, setting screens, rugged rebounding etc.
That may be Zizic's ceiling: Aron Baynes. But you know what? That's pretty good for a guy drafted #23 who will make $1.6m this year.