The op counters provided in serverStatus are not calculated in the same way as the values returned by the top command. This means that it is not currently possible to find values for per-collection op counters that align with the server level op counters returned by serverStatus. It would be nice if per-collection op counter could be collected in the same way as those returned by serverStatus so that the values could be compared to one another. The best place to store and return such statistics is probably the collStats command, as returning the data as part of serverStatus would potentially produce a large increase in the size of the data returned.