The workgen output considers the close time as part of run time. Instead of combining, separating them helps to track operations per second better. The difference between the run time and close time is :
Run time - Configured run time of workload.
Close time - Total time of workload run, including the wait time for all threads to complete their run. A single workload worker taking more time will impact the close time, which might skew the operations per second. If a workload worker is periodically sleeping between the operations, this skew is more. This makes it harder to compare operations per sec.
Update workgen to use the run time to calculate the ops per sec instead of the close time.