Why are there so many problems with lefties?

Most people assume lefties are good, they usually aren't
Players usually do not find the type of leg lift the pitcher throws from
high, medium, or low
Players turn their head before this window and it makes them vulnerable vs. bad lefties
It can be a little strange to shuffle when someone is looking at you
How good is his pickoff?
If it is bad - just keep your eyes up when you land your shuffle to see an obvious difference from his delivery