Appear to mix when playing in ballpark (11)

I believe the answer is:
approximate
'appear to mix when playing in ballpark' is the definition.
I can't tell whether this definition defines the answer.
'appear to mix when playing' is the wordplay.
'when playing' indicates an anagram.
'appear'+'to'+'mix'='appeartomix'
'appeartomix' is an anagram of 'APPROXIMATE'.
Can you help me to learn more?
(Other definitions for approximate that I've seen before include "Fairly accurate" , "Come close to" , "Nearly exact" , "Almost accurate - not exact" , "Rough; inexact" .)
