CPU ready time is really relative to what the virtual server is doing, are you seeing performance issues on the application side?

Servers/applicationgs that field small but high volume requests like a web server would suffer quiet a bit from high cpu ready times. Servers/applications that do larger proccessing on small volume generally would not be affected by high cpu ready times.

From the look of the chart you supplied the virtual servers are only hitting 35% cpu usage at their peak, from that you could remove 1 or 2vcpu's and not really impact the performace of the virtual server too much if at all.

The general rule of thumb is to start with 1 or 2(depending on the type of application running) then add if needed.