About throughput

You are comparing the value of 208 K which is all ingress traffic on all interfaces

with a Value of 28K that something IN and something OUT.

What are you trying to do? I don't think adding things will give you something that you'll expect.
That's because of  different things that affect the throughput. See below.

Have a look at the number of packets IN and packets OUT. You will see that you have more than twice the number of packets coming in than going out. 

I don't think it works that way. you have throughput in and throughput out.

Also be aware of different options that affect the throughput, like oneconnect, HTTP cache, compression, irules

https://support.f5.com/csp/article/K9077

1.  That article is pretty good at explaining. 
The traffic flow from a client is seen as In to a virtual server and In to a server. Likewise, the response from the server is seen as Out from the server and Out from the virtual server.

Client IN -> Server IN

Client Out <- Server Out

2. Because the counters are in bytes example sysStatClientBytesOut , to convert it to bits , it is multiplied by 8. Because a byte has 8 bits

3.  The counters have predefined intervals , like this for example:

sysStatClientBytesOut1m

sysStatClientBytesOut5s

sysStatClientBytesOut5m

I think those values are like a snapshot. They are the values at the moment of the capture, let's say.

probably it is 1 s. Not sure.

Client IN -> Server IN

Client Out <- Server Out

15.3k + 7.9k = 28.2 K    not 208 K

well it is written in that article.

The total throughput in and out of the BIG-IP system collected from all interfaces, including traffic processed by all Traffic Management Microkernel (TMM) and Packet Velocity ASIC (PVA)

• In: The ingress traffic to the system through its interfaces
• Out: The egress traffic from the system through its interfaces

In : means total ingress traffic on all interfaces except management.