I completly agree statistics are not that straightforward, not only he plays a lot of garbage time but also his PT is very few so the statistic is more biased.
But even that, I take it as a proof that he should play more. Having this +/- stat means that besides his deffense and turnovers his way of runing the team works quite well. Anyway I'm not surprised with that because +/- appears in NBA stats. And yes, it's most garbage time, but squeeze garbage time as this is not that easy.
What I'm most surprised is things like Tyreke's efficency seems better at SF than either at PG and SG.
http://www.82games.com/0910/09SAC3.HTM
I'll take it as a proof the next "is Tyreke a PG or a SG" debate
I also found funny in Sergio's stats that when the team has had
on court a Rodriguez-Evans-Casspi-Brockman-Thompson lineup or a Rodriguez-Evans-Greene-Brockman-Thompson lineup in the court, the team has won 100% of matches.