sorry but that one number doesn't really tell very much especially in this isolated case. there are plenty of possible explanations such as him potentially playing more minutes against the laker starters than anyone else, him playing more minutes with portland's bench players than anyone else, etc. off the top of my head just from watching the game, i have no idea if either of those would be true or if there is another explanation but there are plenty of ways a simple +/- can be flawed even moreso when using such a small sample size.
and just look at a couple of other things. in 35 minutes outlaw was -18. in just 23 minutes blake was -15. in just 13 minutes oden was -13. in just 5 minutes sergio was -6. wouldn't the +/- be suggesting that they were all actually worse than outlaw?