Saw this in the Wall Street Journal:
We've played seven of those teams and from that:
Only Julius Jones (93 yards in week one) has run for more than the 87 Portis ran for against San Diego
No one has run for more than the 103 yards Portis ran for against Denver
No one has run for more than the 121 yards Portis ran for against Chicago
No one has run for more than the 144 yards Portis ran for against Tampa
But I guess the problem is when he got those runs.