The values should be the number of items per second, not the new items per second.

If you have 5 queries/ops running for 3 seconds you should not see 5, 0, 0 for the first, second, and third lines for that metric (where each line is at 1 second intervals).

If there are N queries/ops running for a long period of time it should never report 0 for any of those intervals during that period.

See Aaron's comment from http://jira.mongodb.org/browse/SERVER-1745