The statit is the individual disks so you need to add up (ignore parity disks) all the results from each of the raid groups to see what is going on. The sysstat is a total for all the IO and if you have just one aggregate life is simple. If you have multiple I think it shows the information for the busiest aggregate and sum total in other areas. Do not forget to take note of chaining as sequential data can have multiple reads/writes during a single IO event. The total is number of read or writes, multiplied by the chain, multiplied by 4k (block size).
How this helps but it has been a long day and I think I should leave others better able to explain.